Physics - SHM Question with Solution | TestHub

The time period of a simple pendulum is given by $T=2\pi \sqrt{\frac{l}{g}}$.

If the pendulum clock is running slow, it means its time period $T$ is greater than the correct value.

To correct the clock, the time period $T$ must be decreased.

Since $T\propto \sqrt{l}$, decreasing the length $l$ of the pendulum will decrease the time period $T$.

Therefore, the length of the pendulum should be reduced.

Answer: reduce the length of pendulum.