Here’s a question which pretty much everyone gets wrong. But the readers of this blog aren’t just a random sample, so I bet most of you will get it right:

Two identical vehicles A and B, both traveling at speed V directly toward the other vehicle, collide exactly head-on. At another test track, car C collides with an indestructible concrete barrier at speed V’. All other things being equal, the crash-test dummy occupants of vehicles A, B, and C will experience the same forces (and therefore injuries) if…

1. V’ = V/2

2. V’ = V

3. V’ = 2V

4. Something else (explain)How might the answer change if the A and B do not have equal masses?

I’ll let my astute readers answer, but I’ll give a place to start for those who want to make sure they’re thinking from a physics perspective. Momentum is mass times velocity. Force is the time rate of change of momentum. Go from there. Also, in this case I have to suggest you not try to find the answer experimentally!