rate of change of momentum
Answers
The momentum (p) of an object is found by multiplying the objects mass (m) in kilograms (kg) by it’s velocity in metres per second (ms-1).
momentum = mass x velocity
p=mv
Momentum is a vector and it’s unit is the kilogram metre per second (kgms-1).
Example; A car of mass 2000 kg is travelling at 32 ms-1. What is its momentum?
p=mv
=2000(32)
=64000 kgms-1)
When a force is applied on a moving body, its velocity changes. Due to change in velocity of the body, its momentum also changes.
Let a force F be applied on a body of mass m for time t due to which its velocity changes from u to v. Then
Initial momentum of the body = mu
Final momentum of the body = mv
Change in momentum of the body in t second
= mv - mu = m (v - u)
Rate of change of momentum
= Change in momentum/ Time
= m(v-u) / t
But acceleration a = Change in velocity / Time
= v - u / t
Therefore Rate of change of momentum = m a
= mass × acceleration
This relation holds true when mass of the body remains constant.
Thus when a force acts on a body, the rate of change in momentum of body is equal to the product of mass of the body and acceleration produced in it due to that force, provided that the mass of the body remains constant.