Momentum

Momentum equation

p = mv

If no external forces are acting, what happens to momentum

It is conserved

State the conservation of momentum in a collision

total momentum before = total momentum after

State the conservation of momentum in an explosion

Forward momentum = backward momentum

Air track

A long piece of metal with small holes along its surfaces, which air is blown through

Explain why air is blown through the air track

Reduces the friction between the trolleys and track so that we can assume no external forces are acting

Momentum experiment

1- Two trolleys are pushed towards each other on an air track such that they collide between the light gates

2- The light gates measure speed before and after the collision

3- Calculate initial and final momentum with p = mv

Momentum 2nd Law formula

Force = change in momentum / time

Explain, using Newton’s 3rd Law, how momentum is conserved in a collision

If object A exerts a force F on object B, object B will exert a force -F on object A for a time Δt. The change in A’s momentum will be -FΔt and the change in B’s momentum will be FΔt. This means that the overall change in momentum is FΔt - FΔt = 0