A simple pendulum with length 1.6 m and mass 21 kg is pulled 20◦ from the vertical and released. If it is allowed to swing until it comes to rest, how much energy was converted into heat? The acceleration of gravity is 9.8 m/s 2 . Answer in units of J

The amount of energy converted into heat energy = 19.86 J

Explanation:

Length, L = 1.6 cm

Mass, m = 21 kg

Angle of lift, x = 20 ° to the vertical

Therefore, height raised, h = L-L×cosx, where x = 20°

We have

1.6-1.6×cos (20) = 0.096 m

From the first law of thermodynamics, energy is neither created nor destroyed but changes from one form to another.

Therefore initial potential energy is converted into kinetic energy, which is finally converted into heat energy.

Potential Energy P.E. = m×g×h = 21 kg × 9.8 m/s^2×0.096 m = 19.86 J

The 19.86 J of potential energy is converted into heat energy