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⚛️ Physics  ·  Laws of Motion  ·  NEET & JEE

A 2000 kg car changes speed from 30 m/s to 20 m/s in 4 s. Average braking force is:

Answer: 5000 N.

  • A 2000 N
  • B 3000 N
  • C 5000 N
  • D 8000 N

Correct answer: C. 5000 N

Explanation: F = m x |delta_v| / t = 2000 x 10 / 4 = 5000 N.

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 →