In a laboratory experiment with simple pendulum it was found it took 36 s to complete 20 oscillations when the effective length was kept that 80 cm. Calculate the acceleration due to gravity from these data.

Explanation

The time period of a simple pendulum is given by
`T=2pisqrt(lg^-1)`
or `g=(4pi^2l)/T^2` ………….i
In tgeh experiment described in the question the time period is
`T=(36s)/20=1.8s`
Thus by i
`g=(4pi^2xx0.80m)/((1.8s)^2)=98.75ms^-2`