Forces

[Cinjin]

---

100 mph impact force. No question about it.

For every action there is an equal and opposite reaction. A good example would be a baseball pitched at 95 mph at a batter. If that batter chooses to bunt the ball, the impact force is not as great, but if the batter swings and makes contact, the impact forced is compounded.

There's no way the impact force is the same on a wall as it is a head-on collision. Both cars are in motion (action). A wall has no action, therefore no reaction. The energy released in a head on collision is compounded by 2.

No question about it. Impact force of head-on collision is simply the sum of the two speeds the cars were traveling at the moment of impact.

---

Newton's third law does indeed state "To every action there is always an equal and opposite reaction". However, you forget that there are two forces involved here (one for each car), so each must have an equal and opposite reaction. Whilst the total force involved in the impact is 100 mph, it has to be spread between both cars equally, since both are contributing to the force equally. Hence, each car will receive the same "reaction" as if they had hit a stationary wall at 50 mph.

This was recently demonstrated by the MythBusters.

Oops I should've read the OP closer.