$(a)$ Define power. Give its $SI$ unit.
$(b)$ Taking the example of a simple pendulum, explain the variations in the forms of energy and the interconversions involved.
$(b)$ Taking the example of a simple pendulum, explain the variations in the forms of energy and the interconversions involved.
(N/A) Power is defined as the rate of doing work. Its $SI$ unit is watt $(W)$.
$(b)$ For a simple pendulum, the interconversion of energy is as shown in the table below:
As the pendulum swings, the total mechanical energy $(PE + KE)$ remains constant, demonstrating the law of conservation of energy.
$(b)$ For a simple pendulum, the interconversion of energy is as shown in the table below:
| Position | Potential Energy $(PE)$ | Kinetic Energy $(KE)$ |
| Extreme position $1$ | Maximum | Zero |
| Between extreme $1$ and mean | Decreasing | Increasing |
| Mean position | Zero | Maximum |
| Between mean and extreme $2$ | Increasing | Decreasing |
| Extreme position $2$ | Maximum | Zero |
As the pendulum swings, the total mechanical energy $(PE + KE)$ remains constant, demonstrating the law of conservation of energy.
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