Fig. 1-1 A race car seriously damaged in an accident.

Fig. 1-1 shows a race car seriously damaged in a car accident. The damage is caused by the enormous force of the collision. Experience tells us that a fast car will be more seriously damaged than a slow one in an accident. It is also apparent that a massive truck will cause more damage to a lamppost than a light car of the same speed (Fig. 1-2). The impact force in an accident is somehow related to the mass and the speed of the vehicles. Fast and massive vehicles will cause more serious damage than slow and light ones.

Fig. 1-2 A heavy truck will cause more damage to the lamppost than a car moving at the same speed.