An insect is at the bottom of a hemispherical ditch of radius 1 m. It crawls up the ditch but starts slipping after it is at height from the bottom. If the coefficient of friction between the ground and the insect is 0.75, then h is:
- (A)0.20 m✓ Correct
- (B)0.45 m
- (C)0.60 m
- (D)0.80 m
Answer: (A)
Solution
As the insect climbs the inside of the bowl, the radius to it makes an angle with the vertical, the normal force is , and the component of gravity along the surface is . Slipping just begins when this driving component equals the maximum friction , i.e. , giving , so and . The height risen above the lowest point is .
JEE Main · 2020 · 06 Sep 2020 · Shift 1 · Single correct option