Aboy on a skateboard is pushed down the sidewalk by a friend. the skateboard rolls for a while but eventually comes to a stop. what force is causing the skateboard to stop rolling?

friction          :)  hope that this helps

Friction sorry i am late just looking at this i hope it helps

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.