In a closed system that has 85 J of mechanical energy, the gravitational potential energy of a weight being lowered by a pulley decreases from 12 J to 9 J. How does the system's kinetic energy change if there is no friction? O A. It decreases from 76 J to 73 J. O B. It increases from 85 J to 94 J. O c. It decreases from 85 J to 76 J. O D. It increases from 73 J to 76 J.
C- it decrease from 85 J to 76 J because it has 85 J mechanical energy. The pulley decreases from 12 J to 9 J which means it lowers by 12. And it lowers by 3.
