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⚛️ Physics  ·  Laws of Motion  ·  NEET & JEE

A block rests on the floor of a truck (g = 10 m/s²). If the truck decelerates at 5 m/s², the minimum coefficient of friction that keeps the block from sliding forward is:

Answer: 0.5.

  • A 0.5
  • B 0.2
  • C 1.0
  • D 0.05

Correct answer: A. 0.5

Explanation: For no sliding, μg ≥ a → μ ≥ 5/10 = 0.5.

incline surfaceθmgNfmg sinθmg cosθ

Free-body diagram of a block on an incline: weight (mg) resolves into mg sinθ along the slope and mg cosθ into the slope, balanced by the normal force N and friction f.

Concept context

Newton's three laws, friction, circular motion, and free body diagrams.

Read the full Laws of Motion notes →