Work, Energy and Power- Objective Questions

26. A body moves a distance of 10 m along a straight line under the action of a force 5 N. If the work was done is 25 joule, the angle which the force makes with the direction of motion of the body is?

  • 0 degree
  • 35 degree
  • 45 degree
  • 60 degree
Click for Answer/Explanation

60 degree

27. Work is done by frictional force ____.

  • is always negative
  • is always positive
  • is zero
  • maybe positive, negative or zero
Click for Answer/Explanation

may be positive, negative or zero

28. A rifle bullet loses (1/20)th of its velocity in passing through a plank. Assuming that the plank exerts a constant retarding force, the least number of such planks required just to stop the bullet is

  • 11
  • 20
  • 21
  • Infinite
Click for Answer/Explanation

11

29. A particle moves along x-axis from x = 0 to x = 5 metre under the influence of a force F = 7 – 2x + 3x². The work done in the process is?

  • 70
  • 135
  • 270
  • 35
Click for Answer/Explanation

135

30. A particle of mass 2 kg travels along a straight line with velocity v = avx, where ‘a’ is a constant. The work is done by net force during the displacement of a particle from x = 0 to x = 4 m is?

  • 2a²
  • v2a²
  • 4a²
Click for Answer/Explanation

4a²

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