Q: An insect crawls from top of a fixed hemispherical umbrella of radius 30/π cm very slowly. The coefficient of static friciton between the insect and surface of umbrella is µs = 1/√3 . Distance travelled by the insect before sliping is
(a) 1 cm
(b) 2 cm
(c) 3 cm
(d) 5 cm
Ans: (d)
Solution: mgsinθ = μmgcosθ
tanθ = μ =1/√3
θ = 30° = π/6
Since , l = rθ = (30/π)×(π/6)
= 5 cm