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MCQ practice · SSC Physics Board questions · Chapter 4: Work, Power and Energy

Mymensingh Board 2022

A person of weight 70 kg climbs a 100 m high hill in 5 minutes. What is his power in watts? [g = 9.8 ms⁻²]

Think it through first, then pick an option.

  1. a 3500
  2. b 1400
  3. c 228.67
  4. d 0.14
Answer and explanation

Correct answer: c 228.67

Work = mgh = 70 × 9.8 × 100 = 68600 J; time 5 min = 300 s; power = 68600 ÷ 300 = 228.67 W. Not changing minutes to seconds gives a wrong value such as 1372.

Why the other options are wrong

  • a 3500: This is not the answer: Work = mgh = 70 × 9.8 × 100 = 68600 J; time 5 min = 300 s; power = 68600 ÷ 300 = 228.67 W. Not changing minutes to seconds gives a wrong value such as 1372.
  • b 1400: This is not the answer: Work = mgh = 70 × 9.8 × 100 = 68600 J; time 5 min = 300 s; power = 68600 ÷ 300 = 228.67 W. Not changing minutes to seconds gives a wrong value such as 1372.
  • d 0.14: This is not the answer: Work = mgh = 70 × 9.8 × 100 = 68600 J; time 5 min = 300 s; power = 68600 ÷ 300 = 228.67 W. Not changing minutes to seconds gives a wrong value such as 1372.