Question

An insect crawls up a hemispherical surface very
slowly. The coefficient of friction between the insect
and the surface is 1/3. If the line joining the centre of
the hemispherical surface to the insect makes an
angle a with the vertical, the maximum possible value
of a is given by
​

Answer 1

Answer:

Suppose the insect can crawl upto a point P

N=wcosα-----(1)

f=frictionalforce=wsinα-----(2)

from (1) and (2)

tanα=fN

In limiting case tanα=μ

Therefore tanα=13

cotα=3

Hence a is the correct answer.