Question

Determine the energy of a swinging pendulum bob at its highest position, at the middle position, and at its lowest position which will be considered the reference level. The length of the string is 1 m and the height of its highest position is 1.5 m. The mass m of the bob is 0.20 kg.

Answer 1

1. $E_1=mgh=0.2\cdot9.8\cdot1.5=2.94\ (J)$

2. $E_2=mgh_1+mv^2/2=mgh_1+mg(h-h_1)=mgh=$

$=0.2\cdot9.8\cdot1.5=2.94\ (J)$

3. $E_3=mv^2/2=mgh=0.2\cdot9.8\cdot1.5=2.94\ (J)$