The force exerted by the oil on the base of the tank

What happens when you slowly pulled the carboard?

Consider two less-than-desirable options. in the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. in the second option you are driving 30 mph and crash head-on into a stationary brick wall. in neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. which of these two situations would result in the greatest impact force?

In which of these cases are the two wave points considered to be in phase with each other?