Which of the following best expresses the definition of a closed system? (2 points) Energy can enter or leave the system but matter cannot. Heat and matter are both able to enter or leave the system. Matter can enter or leave the system but energy cannot. Heat and matter can enter the system but cannot leave the system.

In a heat engine of 1000 j of heat enters the system and the piston does 500 j of work what is the final internal energy of the system if the inital energy was 2000 j we have to do all of these down here 1)write the equation 2)list out your know variables 3)plug the numbers into the equations 4)solve 5)write your solution statemtn that includes inital energuy and final energuy added