One end of a cylindrical glass rod (mu = 1.5) of radius 1.0 cm is rounded in the shape of a hemisphere. The rod is immersed in water (mu= 4/3) and an object is placed in the water along the axis of the rod at a distance of 8.0 cm from the rounded edge. Locate the image of the object.

Explanation

Given, frequency n = 216 rpm `=(216)/(60)`rps
Length of one turn `=(1)/(2)cm`
`therefore` Number of rotations required to move a distance of `1.5cm`,
`N=("Distance")/("Length of one turn")=(1.5)/(1//12)=18`
Therefore, angular displacement `theta=2piN=2pixx18=36pi` rad
`therefore" Angular velocity of the bar",omega=2pin=2pixx(216)/(60)`
`=72pi"rad s"^(-1)`
`therefore" Required time, t"=("Angular displacement"(theta))/("Angular velocity"(omega))=(36pi)/(7.2pi)=5s`