Question

A light pointer fixed to one prong of a tuning fork touches gently a smoked vertical plate. The fork is set vibrating and the plate is allowed to fall freely. Two complete oscillations are traced when the plate falls through 40cm. What is the frequency `(` in Hz `)` of the tuning fork ?

Answer 1

Correct Answer - 7
Here, `m=2, h=40cm, n=?`
Time taken by the plate to fall down,
`t=sqrt((2h)/(g))=sqrt((2xx40)/(980))=(2)/(7)sec`
Frequency of fork, `n=(m)/(t)=(2)/(2//7)=7Hz`