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LESSON NOTES

Linear Momentum
It is defined as the product of mass and velocity of a body.
Momentum is defined as the quantity of motion of the body. It is measured
by mass×velocity, as momentum depends upon velocity, and it depends on the direction
of the motion of the body as well. Momentum is a vector quantity, since velocity is
vector while mass is scalar.
Momentum = Mass X Velocity

p = mv
Unit of momentum is given as:

-1
SI unit kg.m.s
Imagine two friends Sam and Max running in the playground; Sam weighs 30 kilograms
and Max weighs 40 kilograms, both of them are running at the same speed in the same
direction.

 (a) Who has more momentum, and why?
 (b) Who will get hurt more if they hit a wall?
The answer to both the above questions would be Max, because he has more
momentum, as the velocity of Sam and Max is same, their momentum will depend upon
their mass, therefore Max will have more momentum than Sam.
 If an object is at rest its momentum is zero.

Factors affecting momentum:
 Mass of the object- Directly proportional
 Velocity of the object- Directly proportional

Newton's Second Law of Motion
It states that the rate of change of momentum of a body is directly proportional to the
applied force and takes place in the direction in which the force acts.
Mathematical formulation of Newton’s Second Law of Motion:
Let mass of an moving object be m.
Let is initial velocity be u and final velocity be v.
We know that momentum (p) = Mass × velocity
Therefore,
Initial momentum of object = mu
And Final momentum of the object = mv
Therefore, change in momentum = mv – mu