Engineering Mechanics key points mcq

Engineering Mechanics key points.

This is the technical interview questions and answers section for various interview, competitive examinations.

1. The friction experienced by a body, when in motion, is known as dynamic friction

2. The coefficient of restitution for elastic bodies is

Ans. Zero.

3.Coefficient of restitution for perfect elastic bodies is

Ans. 1.

4. The range of projectile on a downward inclined plane is

__________ the range on upward inclined plane for the same

velocity of projection and angle of projection.

Ans. more than

5. The path of the projectile is a

Ans. parabola.

6. The angle of inclination of a vehicle when moving along a circular path __________ upon its mass.

Ans. does not depend

7. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as

C. limiting friction

8. The mechanical advantage of a lifting machine is the ratio of

B. load lifted to the effort applied

09. Static friction is always

C. greater than dynamic friction.

10. A body will begin to move down an inclined plane if the angle of inclination of the plane is __________

the angle of friction.

C. greater than

11. The bodies which rebound after impact that is called

Ans .Elastic bodies

12. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as

Ans .limiting friction

13. The angle between two forces when the resultant is maximum and minimum respectively are

A.0° and 180°

14. A redundant frame is also called __________ frame.

B. imperfect

15. When a rigid body is suspended vertically, and it oscillates with a small amplitude under the action of the force of gravity, the body is known as

B. compound pendulum

16. The motion of the body from one extremity to the other is known as a

Ans. beat.

17. The velocity of a particle moving with simple harmonic motion is __________ at the mean position.

C.maximum

18. A body is said to move or vibrate with simple harmonic motion if its acceleration is directed towards the

Ans. mean position.

19. In ideal machines, mechanical advantage is __________

Velocity ratio.

     A. equal to

20. The angular velocity (in rad / s) of a body rotating at N revolutions per minute is

C.2πN/60

21. The process of finding out the resultant force is called __________ of forces.

Ans. composition

22. The potential energy of a vertically raised body is

__________ the kinetic energy of a vertically falling body.

Ans. equal to

23. Newton's second law motion __________ a relation between force and mass of a moving body.

Ans. gives

24. Noncoplanar concurrent forces are those forces which

Ans. meet at one point, but their lines of action do not lie on the same plane

25.The kinetic energy of a body before

impact is

Ans. more than the kinetic energy of a body after impact.

26. Concurrent forces are those forces whose lines of action

Ans. meet at one point

27. The point, through which the whole weight of the body acts, irrespective of its position, is known as

Ans. center of gravity

28. Which of the following is a scalar

quantity?

Ans. Speed

29. The rate of change of momentum is directly proportional to the impressed force, and takes place in the same direction in which the force acts. This statement is known as

Ans. Newton’s second law of motion

30. The rate of change of displacement of a body is called

Ans. velocity

31. A smooth cylinder lying on a__________ is in neutral equilibrium.

Ans. convex surface

32. In actual machines, mechanical advantage is __________ velocity ratio.

Ans. less than

33. If three coplanar forces acting on a point are in equilibrium, then each force is proportional to the sine, of the Angle

Ans. between the other two.  

34. When the spring of a watch is wound, it will possess

A. strain energy

35. In a screw jack, the effort required to lower the load is __________ the effort required to raise the same load.

Ans. less than

36. The unit of work in S.I. units is

Ans. joule

37. The acceleration of a particle moving with simple harmonic motion is __________ at the mean position.

Ans. zero

38. The total energy possessed by a system of moving bodies

Ans. is constant at every instant

39. In a screw jack, the effort required to lift the load is given by (where W = Load lifted, α = Helix angle, and φ = Angle of friction.)

Ans. P = W tan (α + φ)

40. A couple produces

Ans. Rotational motion

41. For a self-locking machine, the efficiency must be

Ans. less than 50%

42. One joule is equal to

Ans.1 Nm

43. Whenever a force acts on a body and the body undergoes a

displacement, then

Ans.work is said to be done

44. A nonreversible machine is also

called a

Ans. self-locking machine.

45. If the gravitational acceleration at any place is doubled, then the weight of a body will be

Ans. 2g

46. The law of motion involved in the recoil of gun is

Ans.Newton's third law of motion

47. In order to double the period of simple pendulum, the length of the string should be

Ans.quadrupled

48. If the number of pulleys in a system is equal to its velocity ratio, then it is a __________ system of pulleys

Ans.second

49. Two equal and opposite parallel forces whose lines of action are different

Ans. form a couple.

50. The maximum velocity of a particle moving with simple harmonic motion is

Ans.ωr

51. The unit of power in S.I. units are

Ans.watt

52. The resultant of two equal forces P making an angle θ, is given by

Ans. 2Pcosθ / 2

53. The force, by which the body is attracted, towards the center of the earth, is called

Ans. weight

54. Coplaner concurrent forces are those forces which

Ans. meet at one point and their lines of action also lie on the same plane

55. The time taken by a particle for one complete oscillation is known as

Ans. periodic time.

56. One joule means that

A. work is done by a force of 1 N when it displaces a body through 1m

57. Frequency of vibrations means the

Ans. number of cycles per second.  

58. The amount by which the outer edge of the rail is raised, is known as

Ans. super elevation.

59. The angle of inclination of the plane at which the body begins to move down the plane, is called

Ans. angle of friction

60. A ladder is resting on a rough ground and leaning against a smooth vertical wall. The force of friction will act

Ans. zero at its upper end

61. A framed structure is perfect, if the number of members are __________ (2j-3), where j is the number of

joints.

Ans. equal to

For download PDF click here