Question

What is a second’s pendulum?

Answer 1

Hint: Pendulum is a swinging weight suspended from a pivot. Second’s pendulum is a special pendulum with a constant period of time.

Complete step by step answer:
Second’s pendulum was used commonly in vintage clocks. In this pendulum, the tail of the pendulum reaches its extreme position twice in one oscillation. Thus, the time period of a second’s pendulum is two seconds. Its frequency is 0.5 Hz.

Additional information:
If we are considering the time period of second’s pendulum as 2 seconds, we can simply calculate the length of the pendulum.

As we know, we can use the time period equation of a simple pendulum for the calculation of length.
Time period, $$T=2\pi \sqrt{{\displaystyle \frac{l}{g}}}$$, where l is the length and g is the acceleration due to gravity.
We can assign T as 2 seconds and acceleration due to gravity as 9.8 m/s²
$$2=2\pi \sqrt{{\displaystyle \frac{l}{9.8}}}$$
So the length of the second’s pendulum, $$l={\left({\displaystyle \frac{2}{2\pi }}\right)}^2\times 9.8$$
$$l={\left({\displaystyle \frac{1}{\pi }}\right)}^2\times 9.8$$
$$l=0.9929$$
So that, $$l\approx 1m$$

The second’s pendulum has a constant length, around 1 meter in everywhere on the earth.
The second’s pendulum is a type of simple pendulum. A pendulum is a freely swinging weight suspended from a pivot. A slight displacement in the sideways will bring acceleration towards the equilibrium position. When the weight is released, the restoring force and mass of the pendulum makes oscillations about the equilibrium position. It will cause swinging of the pendulum.

Note: It is not healthy to make any inferences from the name of the second's pendulum. For a swing in a particular direction, second’s pendulum takes one second. So, the time period for a complete cycle is two seconds. That’s why it's got the name “second’s pendulum”.