1 End of Chapter TestWatch
Two cars are involved in a head-on collision.
a State two quantities conserved in the collision. 
b The collision between the cars is described as an inelastic collision.
Explain what is meant by an inelastic collision. 
2 A car of mass 1200 kg is travelling along a straight road at a velocity of 25 m s−1
The driver applies the brakes for a duration of 2.0 s.
During this interval, the car decelerates with a magnitude of 4.0 m s−2
Calculate the change in the momentum of the car. 
3 A 2.8-tonne lorry moving at a speed of 30 m s−1
collides into the back of a stationary car
of mass 800 kg on the hard shoulder of the motorway.
During the collision, the lorry and the car get tangled together.
a Calculate the common speed V of the tangled lorry and car. 
b Calculate the loss of kinetic energy in the collision. 
4 A bumper car of mass 300 kg moving at 4.0 m s−1
collides with another bumper car of mass
420 kg moving at 1.5 m s−1 in the opposite direction.
After the collision, the speed of the 300 kg car decreases to 0.50 m s−1
but it carries on moving
in the same direction (see diagram).
Determine the speed v and the direction of the 420 kg bumper car after the collision.