with links to video Momentum is mass x velocity. A lorry traveling slowly may have the same momentum as a tennis ball served at high speed.
Force required to change the momentum of a fast traveling tennis ball to zero depends on how quick it is stopped. If the racquet is pulled back in the direction of motion upon contact , prolong the time to stop it , therefore reducing the force on the racquet. If the racquet is swung towards a fast moving tennis ball thereby reducing the time to stop it , therefore increasing the force on the racquet.
Therefore prolonging time of impact saves life in an accident as the driver is as innocent as the tennis ball for traveling as such great speed. Seat belts and air bag allows more time to stop , thereby reducing the force on the driver. The crumple zone set in the bonnet allows more time to elapse before the car finally stop , thereby reducing the force.
In motorcycle racing, riders fall off their vehicle and slide on the gravel prolonging the time to stop , therefore saving themselves of bone breaking injuries. They wear suits that can protect their skin.
