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Dictionary

Thursday, December 23, 2010

MOTION


Motion

Definition
If an object continuously changes its position with respect to its surrounding, then it is said to be in state of motion.

Rectilinear Motion
The motion along a straight line is called rectilinear motion.


Velocity

Velocity may be defined as the change of displacement of a body with respect time.
Velocity = change of displacement / time
Velocity is a vector quantity and its unit in S.I system is meter per second (m/sec).

Average Velocity
Average velocity of a body is defined as the ratio of the displacement in a certain direction to the time taken for this displacement.
Suppose a body is moving along the path AC as shown in figure. At time t1, suppose the body is at P and its position w.r.t origin O is given by vector r2.
Diagram Coming Soon Thus, displacement of the body = r2 - r1 = Δr
Time taken for this displacement - t2 - t1 = Δt
Therefore, average velocity of the body is given by
Vav = Δr / Δt

Instantaneous Velocity
It is defined as the velocity of a body at a certain instant.
V(ins) = 1im Δr / Δt
Where Δt → 0 is read as "Δt tends to zero", which means that the time is very small.

Velocity From Distance - Time Graph
We can determine the velocity of a body by distance - time graph such that the time is taken on x-axis and distance on y-axis.


Acceleration

Acceleration of a body may be defined as the time rate of change velocity. If the velocity of a body is changing then it is said to posses acceleration.
Acceleration = change of velocity / time
If the velocity of a body is increasing, then its acceleration will be positive and if the velocity of a body is decreasing, then its acceleration will be negative. Negative acceleration is also called retardation.
Acceleration is a vector quantity and its unit in S.I system is meter per second per second. (m/sec2 OR m.sec-2)

Average Acceleration
Average acceleration is defined as the ratio of the change in velocity of a body and the time interval during which the velocity has changed.
Suppose that at any time t1 a body is at A having velocity V1. At a later time t2, it is at point B having velocity V2. Thus,
Change in Velocity = V2 - V1 = Δ V
Time during which velocity has changed = t2 - t1 = Δ t

Instantaneous Acceleration
It is defined as the acceleration of a body at a certain instant
a(ins) = lim Δ V / Δ t
where Δt → 0 is read as "Δt tends to zero", which means that the time is very small.

Acceleration from Velocity - Time Graph
We can determine the acceleration of a body by velocity - time graph such that the time is taken on x-axis and velocity on y-axis.

Equations of Uniformly Accelerated Rectilinear Motion
There are three basic equations of motion. The equations give relations between
Vi = the initial velocity of the body moving along a straight line.
Vf = the final velocity of the body after a certain time.
t = the time taken for the change of velocity
a = uniform acceleration in the direction of initial velocity.
S = distance covered by the body.
Equations are
1. Vf = Vi + a t
2. S = V i t + 1/2 a t2
3. 2 a S = V f2 - V i 2

Motion Under Gravity
The force of attraction exerted by the earth on a body is called gravity or pull of earth. The acceleration due to gravity is produced in a freely falling body by the force of gravity. Equations for motion under gravity are
1. Vf = Vi + g t
2. S = V i t + 1/2 g t2
3. 2 g S = Vr2 - Vi2
where g = 9.8 m / s2 in S.I system and is called acceleration due to gravity.


Law of Motion

Isaac Newton studied motion of bodies and formulated three famous laws of motion in his famous book "Mathematical Principles of Natural Philosophy" in 1687. These laws are called Newton's Laws of Motion. @import "/extensions/GoogleAdSense/GoogleAdSense.css";

Newton's First Law of Motion

Statement
A body in state of rest will remain at rest and a body in state of motion continues to move with uniform velocity unless acted upon by an unbalanced force
.

Explanation
This law consists of two parts. According to first part a body at rest will remain at rest will remain at rest unless some external unbalanced force acts on it. It is obvious from our daily life experience. We observe that a book lying on a table will remain there unless somebody moves it by applying certain force. According to the second part of this law a body in state of uniform motion continuous to do so unless it is acted upon by some unbalanced force.
This part of the law seems to be false from our daily life experience. We observe that when a ball is rolled in a floor, after covering certain distance, it stops. Newton gave reason for this stoppage that force of gravity friction of the floor and air resistance are responsible of this stoppage which are, of course, external forces. If these forces are not present, the bodies, one set into motion, will continue to move for ever.

Qualitative Definition of Net Force
The first law of motion gives the qualitative definition of the net force. (Force is an agent which changes or tends to change the state of rest or of uniform motion of a body).

First Law as Law of Inertia
Newton's first law of motion is also called the Law of inertia. Inertia is the property of matter by virtue of which is preserves its state of rest or of uniform motion. Inertia of a body directly related to its mass.


Newton's Second Law of Motion

Statement
If a certain unbalanced force acts upon a body, it produces acceleration in its own direction. The magnitude of acceleration is directly proportional to the magnitude of the force and inversely proportional to the mass of the body
.

Mathematical Form
According to this law
f ∞ a
F = m a → Equation of second law
Where 'F' is the unbalanced force acting on the body of mass 'm' and produces an acceleration 'a' in it.
From equation
1 N = 1 kg x 1 m/sec2
Hence one newton is that unbalanced force which produces an acceleration of 1 m/sec2 in a body of mass 1 kg.

Vector Form
Equation of Newton's second law can be written in vector form as
F = m a
Where F is the vector sum of all the forces acting on the body.


Newton's Third Law of Motion

Statement
To every action there is always an equal and opposite reaction
.

Explanation
For example, if a body A exerts force on body B (F(A) on B) in the opposite direction. This force is called reaction. Then according to third law of motion.

Examples
1. When a gun is fired, the bullet flies out in forward direction. As a reaction of this action, the gun reacts in backward direction.
2. A boatman, when he wants to put his boat in water pushes the bank with his oar, The reaction of the bank pushes the boat in forward direction.
3. While walking on the ground, as an action, we push the ground in the backward direction. As a reaction ground pushes us in the forward direction.
4. In flying a kite, the string is given a downward jerk and is then released. Thereupon the reaction of the air pushes the kite upward and makes it rise higher.

Tension in a String
Consider a body of weight W supported by a person with the help of a string. A force is experienced by the hand as well as by the body. This force is known as Tension. At B the hand experiences a downward force. So the direction of force at point B is downward. But at point A direction of the force is upward.
These forces at point A and B are tensions. Its magnitude in both cases is same but the direction is opposite. At point A,
Tension = T = W = mg


Momentum of a Body

The momentum of a body is the quantity of motion in it. It depends on two things
1. The mass of the object moving (m),
2. The velocity with which it is moving (V).
Momentum is the product of mass and velocity. It is denoted by P.
P = m V
Momentum is a vector quantity an its direction is the same as that of the velocity.

Unit of Momentum
Momentum = mass x velocity
= kg x m/s
= kg x m/s x s/s
= kg x m/s2 x s
since kg. m/s2 is newton (N)
momentum = N-s
Hence the S.I unit of momentum is N-s.

Unbalanced or Net Force is equal to the Rate of Change of Momentum
i.e., F = (mVf = mVi) / t

Proof
Consider a body of mass 'm' moving with a velocity Vl. A net force F acts on it for a time 't'. Its velocity then becomes Vf.
Therefore
Initial momentum of the body = m Vi
Final momentum of the body = m Vf
Time interval = t
Unbalanced force = F
Therefore
Rate of change of momentum = (m Vf - m Vi) / t ....................... (1)
But
(Vf - Vi) / t = a
Therefore,
Rate of change of momentum = m a = F ..................... (2)
Substituting the value of rate of change of momentum from equation (2) in equation (1), we get
F = (m Vf - m Vi) / t ............................. Proved


Law of Conservation of Momentum

Isolated System When a number of bodies are such that they exert force upon one another and no external agency exerts a force on them, then they are said to constitute and isolated system.

Statement of the Law
The total momentum of an isolated system of bodies remains constant.
OR
If there is no external force applied to a system, then the total momentum of that system remains constant.

Elastic Collision
An elastic collision is that in which the momentum of the system as well as the kinetic energy of the system before and after collision, remains constant. Thus for an elastic collision.
If P momentum and K.E is kinetic energy.
P(before collision) = P(after collision)
K.E(before collision) = K.E(after collision)

Inelastic Collision
An inelastic collision is that in which the momentum of the system before and after the collision remains constant but the kinetic energy before and after the collision changes.
Thus for an inelastic collision
P(before collision) = P(after collision)

Elastic Collision in one Dimension
Consider two smooth non rotating spheres moving along the line joining their centres with velocities U1 and U2. U1 is greater than U2, therefore the spheres of mass m1 makes elastic collision with the sphere of mass m2. After collision, suppose their velocities become V1 and V2 but their direction of motion is along same line as before.


Friction

When two bodies are in contact, one upon the other and a force is applied to the upper body to make it move over the surface of the lower body, an opposing force is set up in the plane of the contract which resists the motion. This force is the force of friction or simply friction. The force of friction always acts parallel to the surface of contact and opposite to the direction of motion.

Definition
When one body is at rest in contact with another, the friction is called Static Friction.

When one body is just on the point of sliding over the other, the friction is called Limiting Friction.

When one body is actually sliding over the other, the friction is called Dynamic Friction.

Coefficient of Friction (μ)
The ratio of limiting friction 'F' to the normal reaction 'R' acting between two surfaces in contact is called the coefficient of friction (μ).
μ = F / R
Or
F = μ R

Fluid Friction
Stoke found that bodies moving through fluids (liquids and gases) experiences a retarding force fluid friction or viscous drag. If the moving bodies are spheres then fluid friction F is given by
F = 6 π η r v
Where η is the coefficient of viscosity,
Where r is the radius of the sphere,
Where v is velocity pf the sphere.

Terminal Velocity
When the fluid friction is equal to the downward force acting on the sphere, the sphere attains a uniform velocity. This velocity is called Terminal velocity.


The Inclined Plane

A plane which makes certain angle θ with the horizontal is called an inclined plane.
Diagram Coming Soon Consider a block of mass 'm' placed on an inclined plane making certain angle θ with the horizontal. The forces acting on the block are
1. W, weight of the block acting vertically downward.
2. R, reaction of the plane acting perpendicular to the plane
3. f, force of friction which opposes the motion of the block which is moving downward.
Diagram Coming Soon Now we take x-axis along the plane and y-axis perpendicular to the plane. We resolve W into its rectangular components.
Therefore,
Component of W along x-axis = W sin θ
And
Component of W along y-axis = W cos θ

1. If the Block is at Rest
According to the first condition of equilibrium
Σ Fx = 0
Therefore,
f - W sin θ = 0
Or
f = W sin θ
Also,
Σ Fy = 0
Therefore,
R - W cos θ = 0
Or
R = W cos θ

2. If the Block Slides Down the Inclined Plane with an Acceleration
Therefore,
W sin θ > f
Net force = F = W sin θ - f
Since F = m a and W = m g
Therefore,
m a = m g sin θ - f

3. When force of Friction is Negligible
Then f ≈ 0
Therefore,
equation (3) => m a = m g sin ≈ - 0
=> m a = m g sin ≈
or a = g sin ≈ ............. (4)

Particular Cases
Case A : If the Smooth Plane is Horizontal Then 0 = 0º
Therefore,
Equation (4) => a = g sin 0º
=> a = g x 0
=> a = 0

Case B : If the Smooth Plane is Vertical Then θ = 90º
Therefore,
Equation (4) => a = g sin 90º
=> a = g x 1
=> a = g
This is the case of a freely falling body.

Motion in two Dimension Projectile Motion

A body moving horizontally as well as vertically under the action of gravity simultaneously is called a projectile. The motion of projectile is called projectile motion. The path followed by a projectile is called its trajectory.


Examples of projectile motion are

1. Kicked or thrown balls

2. Jumping animals

3. A bomb released from a bomber plane

4. A shell of a gun.



Analysis of Projectile Motion

Let us consider a body of mass m, projected an angle θ with the horizontal with a velocity V0. We made the following three assumptions.

1. The value of g remains constant throughout the motion.

2. The effect of air resistance is negligible.

3. The rotation of earth does not affect the motion.



Horizontal Motion

Acceleration : ax = 0

Velocity : Vx = Vox

Displacement : X = Vox t



Vertical Motion

Acceleration : ay = - g

Velocity : Vy = Voy - gt

Displacement : Y = Voy t - 1/2 gt2



Initial Horizontal Velocity

Vox = Vo cos θ ...................... (1)



Initial Vertical Velocity

Voy = Vo sin θ ...................... (2)

Net force W is acting on the body in downward vertical direction, therefore, vertical velocity continuously changes due to the acceleration g produced by the weight W.

There is no net force acting on the projectile in horizontal direction, therefore, its horizontal velocity remains constant throughout the motion.



X - Component of Velocity at Time t (Vx)

Vx = Vox = Vo cos θ .................... (3)



Y - Component of Velocity at Time t (Vy)

Data for vertical motion

Vi = Voy = Vo sin θ

a = ay = - g

t = t

Vf = Vy = ?

Using Vf = Vi + at

Vy = Vo sin θ - gt .................... (4)



Range of the Projectile (R)

The total distance covered by the projectile in horizontal direction (X-axis) is called is range

Let T be the time of flight of the projectile.

Therefore,

R = Vox x T .............. {since S = Vt}

T = 2 (time taken by the projectile to reach the highest point)

T = 2 Vo sin θ / g

Vox = Vo cos θ

Therefore,

R = Vo cos θ x 2 Vo sin θ / g

R = Vo2 (2 sin θ cos θ) / g

R = Vo2 sin 2 θ / g .................. { since 2 sin θ cos θ = sin2 θ}

Thus the range of the projectile depends on

(a) The square of the initial velocity

(b) Sine of twice the projection angle θ.

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The Maximum Range

For a given value of Vo, range will be maximum when sin2 θ in R = Vo2 sin2 θ / g has maximum value. Since

0 ≤ sin2 θ ≤ 1

Hence maximum value of sin2 θ is 1.

Sin2 θ = 1

2θ = sin(-1) (1)

2θ = 90º

θ = 45º

Therefore,

R(max) = Vo2 / g ; at θ = 45º

Hence the projectile must be launched at an angle of 45º with the horizontal to attain maximum range.



Projectile Trajectory

The path followed by a projectile is referred as its trajectory.

We known that

S = Vit + 1/2 at2

For vertical motion

S = Y

a = - g

Vi = Voy = Vo sin θ

Therefore,

Y = Vo sinθ t - 1/2 g t2 ....................... (1)

Also

X = Vox t

X = Vo cosθ t ............ { since Vox = Vo cosθ}

t = X / Vo cos θ



(1) => Y = Vo sinθ (X / Vo cos θ) - 1/2 g (X / Vo cos θ)2

Y = X tan θ - gX2 / 2Vo2 cos2 θ

For a given value of Vo and θ, the quantities tanθ, cosθ, and g are constant, therefore, put

a = tan θ

b = g / Vo2 cos2θ

Therefore

Y = a X - 1/2 b X2

Which shows that trajectory is parabola.





Uniform Circular Motion



If an object moves along a circular path with uniform speed then its motion is said to be uniform circular motion.



Recitilinear Motion

Displacement → R

Velocity → V

Acceleration → a



Circular Motion

Angular Displacement → θ

Angular Velocity → ω

Angular Acceleration → α



Angular Displacement

The angle through which a body moves, while moving along a circular path is called its angular displacement.

The angular displacement is measured in degrees, revolutions and most commonly in radian.

Diagram Coming Soon s = arc length

r = radius of the circular path

θ = amgular displacement



It is obvious,

s ∞ θ

s = r θ

θ = s / r = arc length / radius



Radian

It is the angle subtended at the centre of a circle by an arc equal in length to its radius.

Therefore,

When s = r

θ = 1 radian = 57.3º



Angular Velocity

When a body is moving along a circular path, then the angle traversed by it in a unit time is called its angular velocity.

Diagram Coming Soon Suppose a particle P is moving anticlockwise in a circle of radius r, then its angular displacement at P(t1) is θ1 at time t1 and at P(t2) is θ2 at time t2.

Average angular velocity = change in angular displacement / time interval

Change in angular displacement = θ2 - θ1 = Δθ

Time interval = t2 - t1 = Δt

Therefore,

ω = Δθ / Δt

Angular velocity is usually measured in rad/sec.

Angular velocity is a vector quantity. Its direction can be determined by using right hand rule according to which if the axis of rotation is grasped in right hand with fingers curled in the direction of rotation then the thumb indicates the direction of angular velocity.



Angular Acceleration

It is defined as the rate of change of angular velocity with respect to time.

Thus, if ω1 and ω2 be the initial and final angular velocity of a rotating body, then average angular acceleration "αav" is defined as

αav = (ω2 - ω1) / (t2 - t1) = Δω / Δt

The units of angular acceleration are degrees/sec2, and radian/sec2.

Instantaneous angular acceleration at any instant for a rotating body is given by

Angular acceleration is a vector quantity. When ω is increasing, α has same direction as ω. When ω is decreasing, α has direction opposite to ω.



Relation Between Linear Velocity And Angular Velocity

Consider a particle P in an object in X-Y plane rotating along a circular path of radius r about an axis through O, perpendicular to the plane of figure as shown here (z-axis).

If the particle P rotates through an angle Δθ in time Δt,

Then according to the definition of angular displacement.

Δθ = Δs / r

Dividing both sides by Δt,

Δθ / Δt = (Δs / Δt) (1/r)

=> Δs / Δt = r Δθ / Δt

For a very small interval of time

Δt → 0



Alternate Method

We know that for linear motion

S = v t .............. (1)

And for angular motion

S = r θ ................. (2)

Comparing (1) & (2), we get

V t = r θ

v = r θ/t

V = r ω ........................... {since θ/t = ω}



Relation Between Linear Acceleration And Angular Acceleration

Suppose an object rotating about a fixed axis, changes its angular velocity by Δω in Δt. Then the change in tangential velocity, ΔVt, at the end of this interval is

ΔVt = r Δω

Dividing both sides by Δt, we get

ΔVt / Δt = r Δω / Δt

If the time interval is very small i.e., Δt → 0 then



Alternate Method

Linear acceleration of a body is given by

a = (Vr - Vi) / t

But Vr = r ω r and Vi = r ω i

Therefore,

a = (r ω r - r ω i) / t

=> a = r (ωr- ωi) / t

a = r α .................................... {since (ωr = ωi) / t = ω}



Time Period

When an object is rotating in a circular path, the time taken by it to complete one revolution or cycle is called its time period, (T).

We know that

ω = Δθ / Δt OR Δt = Δθ / ω

For one complete rotation

Δθ = 2 π

Δt = T

Therefore,

T = 2 π / ω

If ω = 2πf ........................ {since f = frequency of revolution}

Therefore,

T = 2π / 2πf

=> T = 1 / f



Tangential Velocity

When a body is moving along a circle or circular path, the velocity of the body along the tangent of the circle is called its tangential velocity.

Vt = r ω

Tangential velocity is not same for every point on the circular path.



Centripetal Acceleration

A body moving along a circular path changes its direction at every instant. Due to this change, the velocity of the body 'V' is changing at every instant. Thus body has an acceleration which is called its centripetal acceleration. It is denoted by a(c) or a1 and always directed towards the centre of the circle. The magnitude of the centripetal acceleration a(c) is given as follows

a(c) = V2 / r, ........................... r = radius of the circular path



Prove That a(c) = V2 / r

Proof

Consider a body moving along a circular path of radius of r with a constant speed V. Suppose the body moves from a point P to a point Q in a small time Δt. Let the velocity of the body at P is V1 and at Q is V2. Let the angular displacement made in this time be ΔO .

Since V1 and V2 are perpendicular to the radial lines at P and Q, therefore, the angle between V1 and V2 is also Δ0, Triangles OPQ and ABC are similar.

Therefore,


ΔV
/
V1
= Δs / r

Since the body is moving with constant speed

Therefore,


V1
=
V2
= V

Therefore,

ΔV / V = Vs / r

ΔV = (V / r) Δs

Dividing both sides by Δt

Therefore,

ΔV / Δt = (V/r) (V/r) (Δs / Δt)

taking limit Δt → 0.



Proof That a(c) = 4π2r / T2

Proof

We know that

a(c) = V2 / r

But V = r ω

Therefore,

a(c) = r2 ω2 / r

a(c) = r ω2 ...................... (1)

But ω = Δθ / Δt

For one complete rotation Δθ = 2π, Δt = T (Time Period)

Therefore,

ω = 2π / T

(1) => a(c) = r (2π / T)2

a(c) = 4 π2 r / T2 .................. Proved

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Tangential Acceleration

The acceleration possessed by a body moving along a circular path due to its changing speed during its motion is called tangential acceleration. Its direction is along the tangent of the circular path. It is denoted by a(t). If the speed is uniform (unchanging) the body do not passes tangential acceleration.

Total Or Resultant Acceleration

The resultant of centripetal acceleration a(c) and tangential acceleration a(t) is called total or resultant acceleration denoted by a.



Centripetal Force

If a body is moving along a circular path with a constant speed, a force must be acting upon it. Direction of the force is along the radius towards the centre. This force is called the centripetal force by F(c).

F(c) = m a(c)

F(c) = m v(2) / r ..................... {since a(c) = v2 / r}

F(c) = mr2 ω2 r ....................... {since v = r ω}

F(c) = mrω2

Monday, November 22, 2010

Ya Rasul-Allah (Ya Muhammad) SAW

   Bismillah Alrahman Alraheem.
After knowing that how several small things are having big impact on our lives, I thought that it is important to fulfill my duty to share my knowledge if it can help anybody learn anything better or teach me anything better.
PLEASE DON’T CONSIDER IT AUTHENTIC. I HAVE MOST BASIC KNOWLEDGE AND IS BELOW EVEN THE STUDENT LEVEL. I AM JUST SHARING MY UNDERSTANDING AND IT’S BASIS.
Couple of days ago a very good and pious friend of me mentioned that saying or placing “ya” with anyone except Allah is shirk. He also mentioned that people tend to get in longer and pointless conversations just because they don’t have sufficient knowledge and they don’t realize the real point of discussion.
Point of discussion in this post is Permissibility of saying Ya Muhammad SAW.
Saying Ya Muhammad SAW (I prefer Ya RasulAllah SAW) is jaiz/permissible. It is not obligatory/Fard, wajib or Sunnat but it is permissible and saying so is not shirk as long as you believe that
  1. He is not the one having authority to fulfill a need or a prayer. Only Allah SWT is authority.
  2. He cannot give you anything or respond to your prayer without Allah’s will.
  3. He is not as present as Allah SWT. Allah’s presence is beyond the limits of time and space whereas our Prophet SAW are physically present in his grave and he listens to salutations made upon him anywhere and then there are angels specifically assigned to gather salutations on him from all over the universe and bring it to him ([Hafidhh Ibn-al-Qayyim, Jala-ul-Afhaan page 145, Mishkat chapter on Salaah al Nabi) .
After you understand what's  summarized above, you can continue reading for the evidence of permissibility confirming that it is not shirk. Please note that these references are taken from various blogs and forums and I am thankful for the knowledge shared.
Ref 1.
A small quote from Tuhfat uth-Thaakireen of Imam Shawkani [translation kindly provided by Sidi Rashad]
Fasl salawaat ul-Mansoosaat :
Section on the Prayers which have been ordained (By Allah in the Kitab and the Sunnah)
————-
Salat ud-Durri wal-Haaja
[The Prayer of Need]
Hadith number 253:
Yutawad-daa wa yusalli rakatayn thumma yad’oo [translation]Make wudu, and pray two rakah (cycles) of prayer and then make the following supplication:
Allahumma inni as’aluka, wa atawajjahu ilyaka bi-Nabiyyika Muhammad (saw) Nabiyyi-Rahma, Yaa Muhammad innee atawajjahu bika ilaa rabbiy fee haaajatee hathihi lituqdaa lee, Allahummah fashaf-fi-hu fee
[translation]O Allah! Verily I ask you, and turn to you through your Prophet Muhammad (saw) the Prophet of Mercy, O Muhammad verily I turn towards my Lord through you to my Lord in this need of mine, to fulfill it, O Allah intercede/cure this!
This hadith has been extracted by Tirmidhi, al-Hakim in his Mustadrak and Nisa’I, and it is from the hadith of Uthman bin Hanif may Allah be pleased with him. He said a blind man came to the Messenger of Allah (saw) and said: O Messenger of Allah Pray for me! He (saw) said: If you wish I will pray for you, but if you wish, you have been patient and this is better for you. He preferred to be supplicated for. The Messenger (saw) instructed him to make Wudu, and to make a perfect Wudu – Nisai’s narration adds in some of the reports (turuq) to make Wudu and pray two Rakah and then the supplication (as above). It was also extracted by Ibn Majah , and al-Hakim in his mustadrak who stated that it is sahih (authentic) according to the criterion of the two shaykhs (Imam Muslim and Imam Bukhari) and his narration had the addition: so he supplicated with this Dua and he arose and was able to see. Tirmidhi said the Hadith is Hasan Sahih (good and authentic) gharib (singular in chain) and we know this narration through this channel only from the Hadith of Abu Jafar and that is not al-Khatmi, these and other Imams have authenticated this narration, Nisa’I is alone in mentioneing the prayer, but Tabarani agreed with him and in mentions the same in some of his reports (turuq) it reports.
In the narration there is dalil (evidence) of the permissibility of Tawassul (taking a means) through the Messenger of Allah (saw) to Allah azza wa-jal with the firm belief (I’tiqad) that the only active agent (Faa’il) is Allah subhanahu wa’ta’aala, for verily He alone is the giver and the preventer, what He wishes, is, and what He does not wish never can be.
—— End Ref 1——–
Please not that it clearly states that “O Muhammad verily I turn towards my Lord through you” . He is not turning towards Prophet SAW but turning to Allah SWT who has actual authority of curing him but he is doing that “through” Prophet SAW.
This reference is normally enough for me and people like me as it comes directly from Prophet SAW. However, I am presenting more below.
Ref 2 (By Shaykh Muhammed Abu Ammar).
The sensitive issue of whether or not Muslims can say the words ‘Ya Rasool Allah’ or ‘Ya Muhammad!’ [May Allah bless him and grant him peace] needs to be clarified, since this issue divides the Muslim community and causes a great deal of friction among the Muslims throughout the world. Basically, there appears to be what we could label as two “schools of thought”. One insists that saying that stating “Ya Rasul Allah is ’shirk’ and that any Muslim proclaiming it in fact goes outside the pale of Islam. Now the other School believes that it is indeed permissible to say so – based on evidences from the Salaf, and the tafsirs of later day scholars. However, they do not insist that one must proclaim this – or that it is even a fard to do so, rather, it is permissible to do so. This is, and always has been, the stance of the Ahl al-Sunna.
Those who believe that it is impermissible to say Ya Muhammad! [May Allah bless him and grant him peace] not only say that there are no evidences to support the permissibility, but also believe that the prefix of Ya, can only be used when that person [who is being called upon] is present, as opposed to being absent. The proclamation of Ya Muhammad, or Ya Rasul Allah [May Allah bless him and grant him peace] is not an innovation [bid'a] that crept in after the first three generations, but contrary to modern misconceptions, was initiated and practiced within these generations, as we shall see, Allah willing. Also, the fact that the later generations did proclaim Ya Muhammad! [May Allah bless him and grant him peace] the death of the Prophet [May Allah bless him and grant him peace], did not prevent them in doing so, even though there were great distances between them and Madina.
As we shall aim to demonstrate to the readers in this chapter, Insha’ Allah, that if it is wrong today [or even Kufr and shirk as some of our brothers declare], to proclaim Ya Muhammad! [May Allah bless him and grant him peace] why then, did the Sahaba, Tab’ee in and the later generations of Muslims do so? Would those brothers who oppose the Muslims of saying Ya Muhammad! [May Allah bless him and grant him peace] apply the same criteria to the first generations of this Umma as they do for the believers of today?
The permissibility of saying Ya! For someone who is not physically present.
One of the main arguments used against the believers on this issue, is the one of the impermisibility of using the prefix Ya [Oh!] to someone who is not physically present.
Innovation in the Language
This understanding of the Arabic language [that of not being able to use Ya! For an absent person] is an innovation [bid'a] in Arabic grammar. To the minority holding this view, it appears that this is the only way of accusing the majority of Muslims to be constantly committing an impermissible deed, or even shirk and kufr as others may profess.
We first would like to invite those who hold the above view, to examine one of the most respected classical dictionaries of the Arabic language, the Lasan al Arab of Ibn Manzur (d. 711 hijri). Ibn Manzur states that Ya! can be applied for either a person who is near, or far from the caller.
[Ibn Manzur al-Afriqi, Lasan al-Arab under the word 'Ya']
Since those Muslims who often claim that saying Ya Muhammad! [May Allah bless him and grant him peace] is shirk, I now propose to examine the views of Ibn Taymiyya on this issue. Why? Well, it is mainly because these very brothers have given Ibn Taymiyya the noble title of Shaykh al Islam, and such, use him as an authority, if not, the foremost, in their attempts to practice Islam as the Salaf [pious predecessors] did.
Ibn Taymiyya writes: When someone calls upon someone else, saying Ya! it may be used in one of two ways – physically or by the knowledge of that person. An example of this is when the Messenger of Allah [May Allah bless him and grant him peace] warned the people at the time of Dajjal: “Yaa ‘ibaadillaahi Fathbutu…” (Oh servants of Allah! Keep your feet steadfast…) The Prophet, Allah bless him and grant him peace, said this to the people who would be present at the time of Dajjal, and who were not yet born.
Another example, is when Sayyidna ‘Ali, may Allah be pleased with Him, was walking through the plain of Karbalah, he said ‘Ya Abu ‘Abd Allah Hussayn, Fasbir! [Oh, (my son) Abu 'Abd Allah Hussayn! Be patient (when facing the enemy in this place]‘ This was because ‘Ali, may Allah be pleased with Him, was informed by the Messenger of Allah, (May Allah bless him and grant him peace), that his son, Hussayn [May Allah be pleased with Him], would be martyred at Karbalah. Sayyidna ‘Ali, may Allah be pleased with Him, called Hussayn despite the fact that he was not present with him, and even though Hussayn could not hear his Father ‘Ali, may Allah be pleased with Him, but remained in his thoughts.
[Ibn Taymiyya, Minhaj-as-sunna, chapter Aswad-al-Qadeem]
The above example demonstrates, as provided by Ibn Taymiyya, that at least in one way, Ya can be used in the Arabic language to call someone who is not physically present, but who is present in the thoughts of the caller, as when Sayyidna ‘Ali, may Allah be pleased with Him, remembered his son and called to him.
Evidence to support the permissibility of saying Ya Muhammad! [May Allah bless him and grant him peace]
Hafidhh ibn al Qayyim writes that the Prophet of Allah, (May Allah bless him and grant him peace) said: Send salutations on me, but send more salutations on Friday. When you recite the salutation, your voice will reach me wherever you are. Some companions asked, ” even after your death?” The Prophet, (May Allah bless him and grant him peace) replied, “Allah has made it unlawful for the earth to decompose my body”.
[Hafidhh Ibn-al-Qayyim, Jala-ul-Afhaan page 145]
Imam Nasa’i narrates that there are specific angels who visit the earth and whose sole duties are to go to the persons who sends salutations upon the Prophet Muhammad, (May Allah bless him and grant him peace), and then to take those salutations to the Prophet Muhammad, (May Allah bless him and grant him peace)
[Mishkat chapter on Salaah al Nabi]
The above mentioned Ahadith, indicate that if anyone were to send salutations to the Prophet, (May Allah bless him and grant him peace), he himself would either hear the salutations, or an angel will convey them to him. In both cases, salutations will reach the Prophet, (May Allah bless him and grant him peace).
The Salaf used to say Ya Muhammad! [May Allah bless him and grant him peace]
Imam Bukhari, Hafidhh Ibn Taymiyya and Qadi Shawkani all posed the same question, that if a person’s foot becomes numb, what should he do? Their recommendations were the same, and included with their answer, the following hadith:
Some time after Rasul Allah, (May Allah bless him and grant him peace), had passed away, ‘Abd Allah Ibn ‘Umar [May Allah be pleased with Him] was in Najd where one day his foot became numb. As a remedy to alleviate the pain, a person said to him. “Remember the one whom you love the most!” Upon hearing this Ibn ‘Umar [May Allah be pleased with Him] said “Ya Muhammad! [May Allah bless him and grant him peace]” and his foot made an immediate recovery from numbness.
[Imam Bukhari, Adab al Mufrad al Kalim al Tayyab; Hafidhh Ibn Taymiyya and Qadi Shawkani, Tuhfah al Dakireen chapter on Khadirat Rijluhu, and also Imam Nawawi's Kitab al Adkar]
Hafidhh Ibn Taymiyya writes, In the same way as ‘Abd Allah ibn Umar’s foot became numb and he remembered the one he loves the most, ‘Abd Allah Ibn Abbas’s foot also became numb. Someone also said to him to remember the one who he loves the most, whereupon ‘Abd Allah Ibn Abbas said Ya! Muhammad [May Allah bless him and grant him peace] and his foot immediately recovered from numbness.
[Hafidhh ibn Taymiyya, Al Kalim al Tayyib chapter on Khadirat Rijluhu]
Qadi Shawkani writes: If one is in trouble or is in distress, he should perform two nawafil rakats and then make a supplication. They should say ”Ya Muhammad!” [May Allah bless him and grant him peace] and Allah most High will grant them what they requested and their problems and troubles should be resolved. The scholars of hadith say that this hadith is authentic and Tirmidhi, Hakim, Nasa’i, Ibn Majah and at-Tabarani record it.
[Qadi Shawkani, Tofah al Dhakireen chapter on Salaah al Hajah]
Hafidhh Ibn Kathir, Imam Tabari and Imam Ibn Athir all wrote [that]: During the Khilafa of Abu Bakr as- Siddique, may Allah be pleased with Him, there was a battle against the false Prophet Musaylima [of Najd]. When the battle commenced, the Muslims lost their footing at which point Khalid bin Walid, may Allah be pleased with Him, and the rest of the companions called out “Ya Muhammad!” [May Allah bless him and grant him peace] and proceeded to win the battle.
[Tarikh at Tabari, Tarikh Ibn Kathir and Tarikh Qamil by Imam Tabari, Hafidhh Ibn Kathir and Imam Ibn Athir and Ibn Jarir in Chapter Musaylima Kadhaab]
Hafidhh Ibn Kathir and Imam Tabari both write: During the Khilafah of ‘Umar, may Allah be pleased with Him, there was a famine outside the city of Madinah. A companion called Bilal bin Harith al Muzni, may Allah be pleased with Him, said to his people “The famine is very severe, [let us] sacrifice a goat”. Apart from a red bone nothing came from the goat [the goat was very thin due to famine and as such, there was no meat on the bones]. Bilal bin Harith, may Allah be pleased with Him, called out “Ya Muhammad!” [May Allah bless him and grant him peace]. The Messenger of Allah, (May Allah bless him and grant him peace), then appeared in the dream of Bilal bin Harith and informed him that there will be rain.
[Tarikh Ibn Kathir and Ibn Jarir chapter of khilafah of 'Umar (May Allah be pleased with Him]
As-Sayyid Mawdudi writes: When Hajaj bin Yusuf had placed tax upon some new Muslims, they left Basra crying with their fuqaha [scholars] and they were all saying, Ya Muhammad!, Ya Muhammad! [May Allah bless him and grant him peace]
[Sayyid Mawdudi, Khilafah wa Malukiyat, page 270 and Tarikh Ibn Athir]
Hafidhh Ibn Kathir and Imam Tabari both write that After the occasion of Karbala, Sayyida Zaynab, May Allah be well pleased with her, [the sister of Hussayn, may Allah be pleased with Him] and her company were taken as prisoners to Syria. When she passed the dead bodies she proclaimed: “Ya Muhammad!” [May Allah bless him and grant him peace] Your Hussayn is drenched in blood without a shroud or a grave, and Ya Muhammad! [May Allah bless him and grant him peace], your daughters are taken prisoners and your children have been killed
[Ibn Jarir and Tarikh Ibn Kathir in Chapter of Karbala*]
*For those of us, who have forgotten, Karbala took place in Iraq in 60AH. At that time Zaynab may Allah be well pleased with her, said ‘Ya Muhammad! [May Allah bless him and grant him peace]
Imam Waqdi writes: During the khilafah of Abu Bakr Siddiq [may Allah be pleased with Him], there was a battle at Halb. Ka’ab. Abu Bakr [may Allah be pleased with Him] said “Ya Muhammad! Ya! Muhammad, [May Allah bless him and grant him peace] and shouted, “Oh Companions! Stay firm footed!”
['Allama Waqdi, Futoohusham, in the chapter on the Battle of Halb]
Imam Ibn Sa’ad writes: After the Messenger of Allah, (May Allah bless him and grant him peace), had passed away, Arwa bint ‘Abd al Muttalib, May Allah be well pleased with her, recited the: “Ya Rasul Allah! [May Allah bless him and grant him peace]. You were our place of hope.”
[Imam Ibn Sa'ad, Tabaqat Ibn Sa'ad, chapter on the Death of the Prophet]
Hafidhh Ibn al Qayyim writes: Muhammad bin ‘Umar, may Allah be pleased with Him, relates: ‘I was sitting in the company of Abu Bakr bin Mujahid in Baghdad when Shaykh Shibli came before them. Whereupon Abu Bakr bin Mujahid stood up and hugged Shaykh Shibli, kissed his forehead and sat him by his side.’ Muhammad bin ‘Umar [May Allah be pleased with Him] enquired: “You are the Shaykh [Abu Bakr bin Mujahid] whilst the whole of Baghdad regards Shibli as Majnun [Mad] – why have you treated him with so much respect?” To this, Abu Bakr bin Mujahid replied “I have done nothing strange, I have treated him exactly as I have seen the Messenger of Allah, (May Allah bless him and grant him peace), treat him. In my dream I saw the Messenger of Allah, (May Allah bless him and grant him peace), kiss Shibli between his two eyes. I asked the Prophet, (May Allah bless him and grant him peace), “Why did you treat Shibli in this way?” to which he, (May Allah bless him and grant him peace), replied “I love him because after every Salaah he recites the last verse of Surah Tauba after which he recites Sallal la ho ‘alayka Ya Muhammad! [Peace and blessings from Allah be upon you Oh Muhammad!) Three times.
[Hafidhh Ibn-al-Qayyim, Jala-al-Afham., page 80]
The above mentioned Ahadith clearly illustrate that the Companions and others of the Salaf used to say Ya Muhammad or Ya Rasul Allah! [May Allah bless him and grant him peace] when they experienced difficulty, and that the Prophet, (May Allah bless him and grant him peace) did help us either by making supplication for their success or appearing in their dreams to comfort them. Those Companions who were ill and said Ya Rasul Allah [May Allah bless him and grant him peace] found that they would get better; and if they were in a battle which they were losing – they would soon win; and if they were facing a famine – they would soon have rain.
The last quotation from Hafidhh Ibn al-Qayyim shows that the Messenger of Allah, (May Allah bless him and grant him peace), loves the one who pronounces ‘Ya Muhammad!’ [May Allah bless him and grant him peace] to a considerable high degree. All these occurances took place many years after the Messenger of Allah, (May Allah bless him and grant him peace), passed away. So if it was kufr to say ‘Ya Muhammad!’ [May Allah bless him and grant him peace] today and after the lifetime of the Prophet, (May Allah bless him and grant him peace), the Prophet, (May Allah bless him and grant him peace), would not have expressed any love for Shibli. Also, if this is an unreliable narration, why did Ibn al-Qayyim choose to quote it? Was he someone who supported shirk or kufr?
What has been said above supports the fact that it is not kufr or shirk to call out Ya Muhammad, (May Allah bless him and grant him peace).
However, still people will insist, despite of all the above, that to say Ya Muhammad (May Allah bless him and grant him peace) is shirk, and will deduce to the fact that this is a form of worshipping someone besides Allah. They often put forward the following ayat of the Qur’an:
“And the mosques are only for Allah, so worship none with Allah”
[Surah al Jinn verse 18]
This is just a doubt and a misunderstanding of the grammatical use of the words Tad`u/Yad`u in the Arabic language – since Tad’u and Yad’u have been used in two different contexts in the Qur’an: in the context of worship and also in the context of calling.
In the above verse it has been used in the context of worship and we agree that anyone who worships something besides Allah is a kafir and a mushrik. However, when a Muslim says Ya Rasul Allah! [May Allah bless him and grant him peace] he is not worshipping the Messenger of Allah, but merely calling him, as Ibrahim, peace be upon him, called all the people to Hajj [Tafsir Ibn Kathir under Surah Hajj] and as ‘Umar, may Allah be pleased with Him, called Sariah. This type of calling is not worship, of which an example is provided in the Qur’an when Allah commanded Ibrahim, peace be upon him, to call the dead birds [Surah Al- Baqara, verse 260]
This should demonstrate that the word ‘call’ is not always used in the context of worship. Whoever says Ya Muhammad! [May Allah bless him and grant him peace] cannot be called either a kafir or mushrik because he is calling with the love of the Prophet Muhammad, (May Allah bless him and grant him peace), as was the case when the salaf called upon the Messenger of Allah, (May Allah bless him and grant him peace). His intention is not the intention to worship him.
—— End Ref 2——–
Here I have presented what I know and believe and Allah knows the best.
Jul

Kis duniya ka Islam hai yeh

  
Dedicated to any wild animal who labels himself as human and then as Muslim. Any bloody murderer who kills any innocent Muslim or non Muslim and then justifies that Islam taught him to do so. I hate you all. You are not even human and Islam is not even close to you.
I am so hurt. I am hurt for all the pain of innocent humans specifically in my country and at all the places in all the world wherever they are killed/suffered for whatever reason and people doing so called themselves proud Muslims.
I do complain when a non muslim does something terrible. But they are not on the right path. They are not Muslims. But when people do the killings and they are Muslim, it hurts me and my really great and peaceful religion really bad.
~*~ Kis duniya ka Islam hai yeh~*~
Mein kehta hoon insaan nahin
jo khud ko muslim kehte hein
jo kufr mitaney nikle hein
per qatl jo deen ko kerte hein

kya aurat, bachey, bazurg, jawan
nahin dikhte aqal ke maron ko
parhen kalma Nabi pyaarey ka
phir maaren Nabi k pyaaron ko

Islam to hai bas utna sa
k jitna inko suit kiya
dil kiya to jhooti shahadat di
dil kiya to sach ko jhoot kiya

Qaran uthaey hathon mein
aur sar pe sharaa ka parcham hai
eemaan dilon mein ho na ho
bandooq ki goli mein dum hai

jab chaha mimbar loot liye
jab chaha nimazi maar diyey
jab chaha school kiyey veeran
jab chaha baagh ujaar diyey

Per yeh to hamesha haq per hein
jisey yeh maren, taaweel buhut
woh muslim ho ya na muslim
hai inkey paas daleel buhut

aur kaun inhen samjhaye ga
in jhootey numberdaaron ko
Eemaan se khali roohon ko
eemaan ke thekedaron ko

Islam hai deen muhabbat ka
jisey nafrat mein rung daala hai
jiss deen ka tum dam bharte ho
uss deen ka naam uchhala hai

nasamjho, qatl-e-aam hai yeh
diya tum ne naam ibadat ka
tum maasoomon ki jaan bhi lo
aur rakho azm shahadat ka?

kya isko samajhna mushkil hai?
kitna seedha qanoon hai yeh.
ik jaan bhi nahaq li tum ne
to kul insaan ka khoon hai yeh

Aur tum ne kisko nahin mara
aur kiska lehaz yahan baqi
jab khoon baha ker sajde kiye
to rahi nimaz kahan baqi

jo lin tum ne, jo leni hein
kya qeemat hai un janon ki
bas Laanat hai tum logon per
hai laanat sab insaanon ki

Saturday, May 8, 2010

Physics Notes

DEFINITION

"It is the branch of Physics which deals with description of motion without reference to any opposing or external force".


 

MOTION

"When a body changes its position with respect to its surrounding so the body is said to be in the state of motion".

TYPES OF MOTION

There are three types of motion:

1, Linear or Translatory motion

2, Rotatory motion

3, Vibratory motion


 

1. Linear or Translatory Motion

If a body moves in a straight path so the body is to be in Linear motion or Translatory motion.

Example

A bus is moving on the road, A person is running on the ground.


 

2. Rotatory Motion

If a body spins or rotates from the fixed point ,so the body is to be in Rotatory motion.

Example

The blades of a moving fan, The wheel of a moving car.


 

3. Vibratory Motion

To and fro motion about the mean point so the body is to be in Vibratory motion.

Example

Motion of a spring.


 

REST

"When a body does not change its position with respect to its surrounding so the body is said to be in the state of rest".

Example

A book is laying on the table,A person is standing on floor,A tree in the garden.


 

SPEED

"The distance covered by a body in a unit time is called speed."

OR

"The rate of change of distance is called speed."


FORMULA

Speed = Distance/Time

or V = S/t


UNIT

The S.I unit of speed in M.K.S system is Meter/second.

or m/s

Kinds Of Speed

1. Uniform Speed

If a body covers an equal distance in equal interval of time so the body is said to be in uniform speed.

2. Variable speed

If a body does not cover an equal distance in equal inteval of time so the body is said to be in variable speed.


 

VELOCITY

"The distance covered by a body in a unit time in a particular direction is called velocity."

OR

"The rate of change of displacement is called speed."

OR

"Speed in a definite direction is called velocity."


FORMULA

Velocity = Displacment/Time

or V = S/t


UNIT

The S.I unit of Velocity in M.K.S system is Meter/second.

or m/s


 

Kinds Of Velocity

1. Uniform Velocity

If a body covers an equal distance in equal interval of time in a Constant direction so the body is said to be in uniform Velocity.

2. Variable Velocity

If a body does not cover an equal distance in equal interval of time in a particular direction so the body is said to be in variable velocity.


 

ACCELERATION

"The rate of change of velocity is called acceleration."

OR

"Acceleration depends upon the velocity if the velocity continously increases or decreases the accelerattion will be produced."


1. Positive Acceleration

If the velocity continously increases then the acceleration will be positive.

2. Negative acceleration

If the velocity continously decreases then the acceleration will be negative.


FORMULA

Acceleration = change of velocity/Time

or a = (Vf-Vi)/t


UNIT

The S.I unit of Velocity in M.K.S system is Meter/second+square

or m/S2


 

EQUATION OF MOTION

The relationship of initial velocity, final velocity, acceleration, time,and linear distance.


 

FIRST EQUATION OF MOTION

suppose an object moves with initial velocity "Vi" in a time "t" and covers a distance "S" in an acceleration "a" and the final velocity of an object becomes "Vf"

According to the defination of the acceleration "The rate of change of velocity is called acceleration"

i.e. Acceleration = Change of velocity/time

=> a = Vf - Vi/t

DERIVATION

a = Vf - Vi/t

at = Vf - Vi

or Vf = Vi + at


 

SECOND EQUATION OF MOTION

According to the definition of the acceleration "The rate of change of velocity is called acceleration".

i.e. Acceleration = Change of velocity/time

=> a = Vf - Vi/t

at = Vf - Vi

or Vf = Vi + at -------------(1)

Substituting the average velocity:

Vav = (Vi + Vf)/2 -----------(2)

The distance covered by the body in a unit:

S = Vav/t

Putting the value of Vav from equation 2:

S = [(Vi + Vf)/2] * t

Putting the value of Vf from equation 1:

S = [(Vi + Vi + at)/2] * t

S = [(2Vi + at)/2] * t

S = (Vi + at/2} * t

S = (Vit + 1/2at2) {Here 2 is the square of the time "t". Dont write this sentence in the examination}


 

THIRD EQUATION OF MOTION

According to the definition of the acceleration "The rate of change of velocity is called acceleration".

Acceleration = Change of velocity/time

=> a = (Vf - Vi)/t

=> at = Vf - Vi

or t = (Vf - Vi)/a -------------(1)

Subsituting the average velocity:

Vav = (Vi + Vf)/2 -----------(2)

We know that:

Vav = S/t

=> S = Vav * t

Putting the value of Vav from equation 2 and value of t from eq 1:

S = [(Vi + Vf)/2] * [(Vf-Vi)/a]

S = Vi2 - Vf2/2a since {(a+b) (a-b) = a2 - b2}

or 2as = Vf2 - Vi2


 

ACCELERATION DUE TO GRAVITY OR FREE FALLING OBJECTS

"Galileo was the first scientist to appreciate that, neglecting the effect of air resistance, all bodies in free-fall close to the Earth's surface accelerate vertically downwards with the same acceleration: namely 9.8 m/s2"

Example

If a ball is thrown vertically upward, it rises to a particular height and then falls back to the ground. However this is due to the attraction of the earth which pulls the object towards the ground"

CHARACTERISTIC OF FREE FALLING BODIES

1, When a body is thrown vertically upward, its velocity continously decreases and become zero at a particular height During this motion the value of acceleration is negative and Vf is equal to zero (a = -9.8m/s2 , Vf = 0).

2, When a body falls back to the ground , its velocity continously increases and become maximum at a particular height During this motion the value of acceleration is positive and Vi is equal to zero (a = 9.8m/s2 , Vi = 0).

3, Acceleration due to gravity is denoted by a and its value is 9.8m/s2 .

4, Equation of motion for the free-falling bodies be written as,

Vf = Vi + gt

h = Vit + 1/2 gt2

2gh = Vf2 - Vi2