Define the Momentum and Impulse.

Momentum, p, is a measure of a car's motion.

  p =  m  v

where p is momentum in kg-m/s, m is mass in kilograms and v is the velocity of the car in m/s. If you have a VW Bug going 50 kph and a semi going at the same speed, which has more momentum? The semi does, of course: the more mass, the more momentum. What about a semi moving at 25 kph and one moving at 50 kph? The semi moving at 50 kph has more momentum. More speed also means more momentum.

Another way to express Newton's Second Law is:

  F = m a

F = m Δv/Δt

F Δ t = m Δ v

where F is the force vector (in Newtons), Δt is the time (in seconds) that the constant force is pushing, m is the mass (in kilograms) of the ball, and Δv is the change in the velocity vector (in m/s). This can also be written

F Δ t = Δ p

where F Δt is the impulse in N-s, and Δp is the change in momentum in kg-m/s.