Q6 - A crane lifts a mass

Last updated at September 16, 2026 by

  • 📋 Revise, Reflect, Refine, Q6 (Page 137)
    A crane lifts a mass m to the 10th floor of a building in a certain time. It then raises the same mass to the 20th floor of the same building in double the time. How much more energy and power are required? Assume that the height of all floors is equal.
    GIF Watch: why does the pendulum eventually stop in real life Q6 - A crane lifts a mass - Work, Energy, and Simp - [Teachoo] - Questions at the end of the chapter
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    Answer
    • Energy
      • Energy = mgh. Height of 20th floor = 2 × height of 10th floor.
      • So energy required is 2 times .
    • Power
      • Power = Work / time
      • Work became 2 times, and time also became 2 times.
      • Power = 2W / 2t = W / t — same as before!
      • So the power required is the same (no more power needed).
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