Question

In a closed system that has 560 J of mechanical energy, the gravitational

potential energy of a weight being lowered by a pulley decreases from 250 J
to 175 J. How does the system's kinetic energy change if there is no friction??
O A. It increases from 560 J to 735 J.
O B. It decreases from 385 J to 310 J.
O C. It decreases from 560 J to 485 J.
D. It increases from 310 J to 385 J.​

Answer 1

the system's Kinetic energy increases from 310 J to 385 J

(which agrees with option D in your list of possible answers)

Step-by-step explanation:

If there is no friction, the initial mechanical energy of the system is 560 J , and the gravitational potential energy varies from 250 J to 175 J,

then we have:

Initial Kinetic energy = 560 J - 250 J = 310 J

Final Kinetic energy = 560 J - 175 J = 385 J

So the system's Kinetic energy increases from 310 J to 385 J