Verified Solution • 2025–26 Session moderate

QJEEM20Ph8563: JEE Main 2020 Physics - Class 11 JEEM20Ph8563 Solution: An insect is at the bottom of a hemispherical ditch of radius 1 …

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 h from the bottom. If the coefficient of friction between the ground and the insect is 0.75, then h is :
(g = 10 ms–2)

Multiple Choice Options

  • A 0.45 m
  • B 0.60 m
  • C 0.20 m
  • D 0.80 m

Step-by-Step Verified Solution

JEE Main 2020 (Online) 6th September Morning Slot Physics - Laws of Motion Question 93 English Explanation 1

For balancing mgsin θ\theta = f

mgsin θ\theta = μ\mu mgcos θ\theta

⇒\Rightarrow tan θ\theta = μ\mu = 34{3 \over 4}
JEE Main 2020 (Online) 6th September Morning Slot Physics - Laws of Motion Question 93 English Explanation 2
h = R – R cos θ\theta

= R - R (45)\left( {{4 \over 5}} \right) = R5{R \over 5}

∴\therefore h = R5{R \over 5} = 15{1 \over 5} = 0.2 m

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