posted by Dani .
A car is stationary at a stop sign when it is hit directly from behind by a truck of mass 3000kg which was travelling at a speed of 9 m/s immediately before the collision. The two vehicles lock together and move forward with an initial speed of 6 m/s.
a) what is the mass of the car?
b) If the car had been designed with a crumple zone, explain in correct physics term, why this might reduce the risk of injury to the driver.