I don’t understand the 4th one please help someone.

Aroller coaster car moving at a velocity of 30 meters/second has a momentum of 2.5 x 10^4 kilogram meters/second. what is its mass?

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

In an experiment, how can i change human errors? be specific.