A fisherman with mass m stands at the center of a small boat which is stationary on the water. The boat also has mass m and is a distance d from the shore. The fisherman walks on the boat toward the shore. Assume there is
no drag force between the boat and water, and that there is no net external force applied to the system.
What happens to the boat?

If the heat engine is a perfect carnot cycle engine, thenefficiency = (t2-t1)/t2   where t1=temperature of cold reservoir ( ° k) = 135            t2=temperature of hot reservoir ( ° k)   = 325thereforeefficiency = (t2-t1)/t2 = (325-135)/325 = 0.5846 = 58%  note: this is the theoretical maximum efficiency of a perfect heat engine.   real-life engines do not achieve this value.

Ithink c because you have to work to become goid