1. which of the following best describes the movement of an object at rest if no outside forces act on it?
it will move due to inertia.
gravity will eventually cause it to move.
it will stay at rest due to inertia.
it will stay at rest due to gravity.

It will stay at rest due to inertia.

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.