In which step of the four-stroke engine cycle does the heat from the combustion reaction cause the pistons to move?

a. combustion and expansion
b. air and fuel intake
c. compression and ignition
d. exhaust

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j? 1. write the equation 2.list out your known variables 3.plug the numbers into the equations 4.solve 5.write your solution statement that includes initial energy and final