Question

Keeping in mind the Law of Conservation of Energy, suppose the pendulum above has 20 joules of PE at Point A. When the pendulum is at Point C, its PE is 0 joules. How much KE does it have at Point C?

a) 20 joules
b) 16 joules
c) 10 joules
d) 8 joules

Answer 1

The pendulum at Point C has 20 joules of kinetic energy according to the Law of Conservation of Energy, because it had 20 joules of potential energy at Point A and energy in a closed system is conserved.

Step-by-step explanation:

Using the Law of Conservation of Energy, we can determine the kinetic energy (KE) of the pendulum at Point C. The problem states that the pendulum has 20 joules of potential energy (PE) at Point A, and that this potential energy drops to 0 joules at Point C. Since there is no indication of energy losses due to friction or air resistance, we can assume that all of the pendulum's initial potential energy has been converted into kinetic energy at the lowest point of the swing (Point C).

According to the principle of conservation of energy, the total mechanical energy (the sum of potential and kinetic energies) of a closed system remains constant if there are no losses. So, at Point C, all the 20 joules of potential energy at Point A has been transformed into kinetic energy. Therefore, at Point C, the pendulum has 20 joules of kinetic energy.

Answer: a) 20 joules