An insect crawls up a hemispherical surface as shown (see the figure) the coefficient offriction between the insect and the surface is 1/3. If the line joining the centre of the hemisperical surface to the insect makes an angle `theta` with the vertical, the maximum possible value of `theta` is given by

Explanation

`N = mg cos theta`………(1)
`mu N = mg sin theta`……..(2)
From (1) and (2), we get:
`cot theta =1//mu = 3 rArr theta = cot^(-1)(3)`