Calculating impulse

Question

A car of 1 tonne travels at a speed of 100km/h collides with a 3 tonne van travelling 20km/h in the same direction. After the collision the car rebounds at 20km/h. Calculate the impulse on the van. 

Answer 1

Impulse = change in momentum = Average force * time of impulse

 

Impulse of car on van = m(V-U)

 

= 1000(-20-100)/3.6,    converting; 1 kph = 3.6 mps

 

= -33,333 kg.s (the negative sign indicates that the direction of this impulse is opposite to the initial direction of the car's motion)