A stack of four physics textbooks sits on top of a desk. The mass of the bottom book is 5.0 kg, on top of which is a 4.5 kg book, then a 4.0 kg book, then a 3.5 kg book. What is the normal force exerted on each book

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