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Question 30261
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Laws of Motion and Friction: JEE — Block Wall MCQ

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JEE — Block WallHardQuestion 30261

Question

A 2 kg block is pressed against a vertical wall by a horizontal force of 40 N. μₛ = 0.4. The block is in equilibrium. The friction force acting on the block is: (g = 10 m/s²)
  1. A
    16 N upward
  2. B
    20 N upward
    Correct
  3. C
    16 N downward
  4. D
    20 N downward

Correct answer

20 N upward

Explanation

The block is in equilibrium vertically: friction = mg = 2×10 = 20 N upward. The normal force = 40 N (horizontal). Max friction = 0.4×40 = 16 N. Since required friction (20 N) > max friction (16 N), the block actually slides down — question is ill-posed if equilibrium is assumed. If the block is in equilibrium, friction = 20 N.

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