21. A stone of mass 1 kg is tied with a string and it is whirled in a vertical circle of radius 1 m. If tension at the highest point is 14 N, then velocity at the lowest point will be?

  • 3 m/s
  • 4 m/s
  • 6 m/s
  • 8 m/s
Click for Answer/Explanation

8 m/s

22. A string is used to pull a block of mass ‘m’ vertically up by a distance ‘h’ at a constant acceleration ‘g/3’. The work done by the tension in the string is?

  • 2mgh/3
  • 4mgh/3
  • mgh/3
  • -2mgh/3
Click for Answer/Explanation

4mgh/3

23. A particle moves along X-axis from x = 0 to x = 1 m under the influence of a force given by F = 3x² + 2x – 10 . Work done in the process is?

  • -8J
  • 8J
  • -4J
  • 2J
Click for Answer/Explanation

-8J

24. A man carries a load on his head through a distance of 5 m. The maximum amount of work is done when he

  • moves it over an inclined plane
  • moves it over a horizontal surface
  • lifts it vertically upwards
  • None of these
Click for Answer/Explanation

lifts it vertically upwards

25. If 250 J of work is done by sliding a 5 kg block up an inclined plane of height 4 m. Work done against friction is (g = 10 m/s²)?

  • 100 J
  • 50 J
  • 150 J
  • Zero
Click for Answer/Explanation

100 J

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