If the mass of a bob of a pendulum is increased by $9$ times, the period of the pendulum will?

$A$ pendulum clock is placed inside an elevator. Under what condition does it show the correct time?

$A$ cylindrical piece of cork of density $\rho$, base area $A$, and height $h$ floats in a liquid of density $\rho_{l}$. The cork is depressed slightly and then released. Show that the cork oscillates up and down simple harmonically with a period $T=2 \pi \sqrt{\frac{h \rho}{\rho_{l} g}}$. (Ignore damping due to viscosity of the liquid).

Two simple pendulums of length $1\, m$ and $4\, m$ respectively are both given small displacement in the same direction at the same instant. They will be again in phase after the shorter pendulum has completed a number of oscillations equal to

If the length of a clock pendulum increases by $0.2 \%$ due to atmospheric temperature rise,then the loss in time of the clock per day is ........... $s$.

The bob of a simple pendulum of length $l$ is made of iron. The pendulum is oscillating over a horizontal coil carrying a direct current. If the time period of the pendulum is $T$,then: