A light pointer fixed to one prong of a tuning fork touches gnetly a smoked vertical plate. The fork is set vibrating and the plate is allowed to fall freely. 8 complete oscilllations are counted when the plate falls through 10cm.What is the frequency of the tuning fork?

Explanation

During the time the plate falls through 10 cm from rest, the tuning fork makes 8 vibrations
From speed equation we get
`h = (1)/(2)"gt"^(2)`
`0.1 = (1)/(2)xx9.8 xx t^(2)` or `t = (1)/(7)s`
In `(1)/(7)s` the fork makes 8vibrations. Therefore in Is, the number of vibrations fork makes is
`n = 8 xx 7 = 56`
Thus frequency offork is
n = 56Hz.