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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 (m/s).

momentum = mass x velocity

p=m x v

Momentum image 1

Momentum is measured in kilogram metre per second (kg m/s).

Example; A car of mass 2000 kg is travelling at 32 m/s. What is its momentum?

momentum calc 3

The law of conservation of momentum

When two objects interact the total momentum remains the same  provided no external forces are acting (a closed system).

The momentum before = the momentum after.

Example;  A toy car of mass 8 kg is travelling at 20 m/s. It collides with a car of mass 3 kg which is stationary. The two cars join together and move of as one object, what is the velocity of the two cars as they move off together?

momentum example 1 momentum calc 1

Example; Two objects are in stationary and in contact with each other. They are pushed apart by an explosion. The 3 kg toy car moves right with a velocity of 14 m/s and the 8 kg car moves left. What is the velocity of the 8 kg toy car as it moves left?

momentum example 2 momentum calc 2