Question

A 1.0 kg pendulum has an initial total energy of 10 J. Calculate the energy lost as heat if the pendulum is 0.10 m high and is traveling at 4.0 m/s.

Answer 1

Lost energy = 2J

Explanation: Given that the

Mass of the pendulum M = 1.0kg

Initial energy E = 10J

Height h = 0.1 m

Speed V = 4 m/s

Let us use conservation of energy to analyze the senero

The maximum P.E at the initial position will be equal to maximum P.E for travelling down the hill

I.e

Total P.E = total K.E

K.E = 1/2MV^2

K.E = 1/2 × 1 × 4^2

K.E = 8J

Since P.E = K.E

P.E = 8J

But initially energy E = 10J

Lost energy = P.E - E

Lost energy = 10 - 8 = 2J