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An insect crawls up a hemispherical surf...

An insect crawls up a hemispherical surface very slowly (see the figure). 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 `alpha` with the vertical, the maximum possible value of `alpha` is given by

A

`cotalpha=3`

B

`tan alpha=3`

C

`sec alpha=3`

D

`cosec alpha =3`

Text Solution

Verified by Experts

The correct Answer is:
A
`N= mg cos alpha` ,br> `:.f= mu N=mu mg cos alpha`

and `f=mu N=mg sin alpha`
`:.mu mg cos alpha=mg sin alpha`
`implies cot alpha=(1)/(mu)=3`
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