GCSE Physics AQA 8463

**Momentum is a property of moving objects

Momentum is defined by the equation:

$\text{momentum} = \text{mass} × \text{velocity}$

$p = m v$

momentum, p, in kilograms metre per second, kg m/s mass, m, in kilograms, kg velocity, v, in metres per second, m/s**

**Conservation of momentum

In a closed system, the total momentum before an event is equal to the total momentum after the event.

This is called conservation of momentum.

Students should be able to use the concept of momentum as a model to:

• describe and explain examples of momentum in an event, such as a collision
• complete calculations involving an event, such as the collision of two objects.**

**Changes in momentum

When a force acts on an object that is moving, or able to move, a change in momentum occurs. hrThe equations $F = m a$ and $a = \dfrac{v-u}{t}$

combine to give the equation $F = \dfrac{m \Delta v}{\Delta t}$

where m∆v = change in momentum

ie force equals the rate of change of momentum. hrStudents should be able to explain safety features such as: air bags, seat belts, gymnasium crash mats, cycle helmets and cushioned surfaces for playgrounds with reference to the concept of rate of change of momentum. hrStudents should be able to apply equations relating force, mass, velocity and acceleration to explain how the changes involved are inter-related.**