A simple pendulum, while oscillating rises to a maximum vertical height of 5 cm from its rest position. Assume its rest position is at ground level. If the mass of bob of the simple pendulum is 500 g and acceleration due to gravity g = 10 m/s2. Find the below:
i) The total energy of simple pendulum at any instant while oscillating.
ii) The velocity of bob at its resting position.
0.25 J, 1 m/s
Given,
Mass m = 500 g = 0.5 kg
Height h" = 5 cm = 0.05 m
Assuming there is no loss in energy due to air friction,
(i) Total energy of simple pendulum
= Potential energy at its extreme position
= mgh = 0.5×10×0.05 = 0.25 J
(ii) Kinetic energy at a mean position
Change in PE = Change in KE
= 12mv2 = mgh
or v =√2gh = √2×10×0.05 = √1
= 1 ms−1