و By assuming that a hydrogen atom consists of an electron of charge ē orbiting a proton of charge e calculate the ratio of the electric force between
the electron and the proton to the gravitational force between them. [Given that mass of ē = 9.1 x 10^-31kg, mass of e= 1.64×10^-27kg, G = 6.67×10^-11]

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