Can someone please help me with science.

Asun-sized star will spend most of its lifetime as a: white dwarf red giant protostar main-sequence star

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

Your friend increases her force on the desk by 30n . she doesn't change the direction of her push . what happens to the net force on the desk .will the desk accelerate