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

60 degree

27. Work is done by frictional force ____.

• is always negative
• is always positive
• is zero
• maybe positive, negative or zero

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

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

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