Question

Assume in a certain collision, a car going 60 mph collides with a wall that does not move. in another collision, the same car going 60 mph collides head-on with an identical car going 60 mph. is the impact in the first collision the same as the impact in the second collision? explain.

Answer 1

Well, from a stationary reference frame, after the crash both cars remain at rest, so the kinetic energy dissipated is2( 0.5*mv^2)= mv^2

From the reference frame moving with the first car, the kinetic energy before the crash is 0.5mv^2= but after the crash, the cars do not remain at rest but keep moving in the direction of the second car at half the speed. So, of course, the kinetic energy after the crash is 0.5*mv^2)= mv^2, and the total kinetic energy lost in the crash is the same as when considering a stationary reference frame.

In the car against a wall, you do have the full dissipation of a kinetic energy of 0.5mv^2.It is no same impact