Question

When a pendulum is at the position all the way to the left when it is swinging (at the top of the arc), what is true of the kinetic and potential energy? A) The potential energy is zero, and the kinetic energy is maximized. B) The kinetic energy is zero, and the potential energy is maximized. C) Both the kinetic and potential energy are zero. D) Both the kinetic and potential energy are at their maximum. D) There is no energy at this position.

Answer 1

Choice - B is the correct one.

At the top of the arc, at one end of the swing:
-- it's not going to get any higher, so the potential energy is maximum
-- it stops moving for an instant, so the kinetic energy is zero

At the bottom of the arc, in the center of the swing:
-- it's not going to get any lower, so the potential energy is minimum
-- it's not going to move any faster, so the kinetic energy is maximum