a 3.0m long frictionless pendulum swings with a maximum angluar displacement of 10 degree from the vertical. at its lowest position the kinetic energy of the pendulum is 20.0j what is the potential energy of the pendulum when the kientic energy is 5.0j

The P. E of the pendulum is, P. E = 15 J

Explanation:

Given data,

The length of the pendulum, l = 3 m

The maximum angular displacement from vertical, Ф = 10°

The K. E at its lowest position is, K. E = 20 J

The total mechanical energy of the system is equal to the sum of its K. E and P. E

E = K. E + P. E

At the lowest position P. E = 0

Therefore, The total mechanical energy,

E = 20 J

When the K. E of the pendulum is K. E = 5 J

E = K. E + P. E

P. E = E - K. E

= 20 - 5

= 15 J

Hence, the P. E of the pendulum is, P. E = 15 J