a laboratory cart mi=500g is pulled horizontally across a level track by a lead weight m2=25g suspended vertically off the end of a pulley. If the lead weight falls 85cm then find speed of the system

Yes

The answer is orbit around nucleus

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.

It would stay the same