In this graph of potential energy vs.x, the horizontal line represents the total mechanical energy of a particle.Approximately what is its kinetic energy at x = 15 m?
A)5 J
B)10 J
C)15 J
D)20 J
E)25 J

Question

In this graph of potential energy vs.x, the horizontal line represents the total mechanical energy of a particle.Approximately what is its kinetic energy at x = 15 m? 
A)5 J 
B)10 J 
C)15 J 
D)20 J 
E)25 J

Quizplus · Accepted Answer

At x = 15 m, the total mechanical energy is approximately 20 J (the height of the horizontal line). To determine the kinetic energy, we subtract the potential energy at x = 15 m from the total mechanical energy. The potential energy at x = 15 m is approximately 0 J (the height of the curve at x = 15 m). Therefore, the kinetic energy is approximately 20 J - 0 J = 20 J. Since the closest choice is 20 J, the answer is D.

In This Graph of Potential Energy Vs