What is the time tb it will take for point b of the wavefront to encounter the vacuum/material interface? note that you will express your answer in a slightly unusual way. express your answer numerically in units of t1 (the time it takes light to travel a distance d in a vacuum). use three significant figures. view available hint(s)

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