Momentum - GCSE Physics Definition

What is momentum?

In GCSE physics, momentum is a property of an object with mass when it is in motion. 

The equation for momentum is:

p = mv

Where:

• p = momentum, measured in kilogram metres per second (kg m/s)

• m = mass, measured in kilograms (kg)

• v = velocity, measured in metres per second (m/s)

When an object is not moving, its momentum is zero. An easy way to remember momentum is ‘mass in motion’. Momentum is a vector quantity, which means it has both magnitude and direction.

If a car of mass 1500 kg has a velocity of 20 m/s, then its momentum is 1500 kg × 20 m/s = 30 000 kg m/s. A smaller car can have the same momentum if it travels faster, and a larger car can have the same momentum if it travels more slowly.