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
27. Work is done by frictional force ____.
- is always negative
- is always positive
- is zero
- maybe 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
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
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?
- a²
- 2a²
- v2a²
- 4a²