Aheat engine absorbs 2500 j of heat from a hot reservoir and expels 1000 j to a cold reservoir. when it is run in reverse, with the same reservoirs, the engine pumps 2500 j of heat to the hot reservoir, requiring 1500 j of work to do so. find the ratio of the work done by the heat engine to the work done by the pump. is the heat engine reversible?

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?