Question

A simple pendulum makes 120 complete oscillations in 3.00 min at a location where g = 9.80 m/s2. Find the period of the pendulum.

Answer 1

a)T = (3 x 60)/120 = 1.5 sec

(b)By T = 2 x pi x sqrt[L/g]

=>1.5 = 2 x 3.14 x sqrt[L/9.8]

=>L/9.8 = (0.24)^2

=>L = 9.8 x 0.057 = 0.56m

Answer 2

Given:

• 120 oscillations made in 3 minutes.
• g = 9.8 m/s².

To find:

• Time period of pendulum ?

Calculation:

• Time period of a pendulum is defined as the time taken by the body to complete one full oscillation.

So, using Unitary Method :

120 oscillations made in 3 min (or 180 seconds).

=> 1 oscillation made in $\:\dfrac{180}{120}=1.5 sec$

Hence, time period is 1.5 seconds

Extra information:

• Frequency is the reciprocal of time period. In this case , frequency = 1/1.5 = 0.67 Hz.