51. Frictional force encountered after commencement of motion is called dynamic friction.

52. A projectile is fired at an angle to the vertical, its horizontal range will be maximum when angle is 45 degree.

53. Limiting force of friction is the friction force acting when the body is just about to move.

54. Coulomb friction is the friction between bodies having relative motion. (T/F)

Ans. True.

55. Dynamic friction as compared to static friction is less.(true)

56. Kinetic friction is the friction force acting when the body is in motion.(T/F)

Ans. True.

57. The algebraic sum of moment of the forces forming couple about any point in their plane is equal to the moment of the couple.

58. A single force and a couple acting in the same plane upon a rigid body

1. balance each other
2. cannot balance each other
3. produce moment of couple
4. are equivalent
5. none of above

Ans. b) cannot balance each other

59. The necessary condition for forces to be in equilibrium is that these should be

1. coplanar
2. meet at one point
3. both (a) & (b)
4. all be equal
5. something else

Ans. c) both (a) & (b)

60. if n= number of members and  j= number of joints, then for a perfect frame, n=2j-3.

Engineering Mechanics or Applied Mechanics Important Question

61. A body moves , from rest with a constant acceleration of 5 m per sec. The distance covered in 5 sec is most nearly

a) 38m    b) 62.5 m     c) 96 m    d) 124 m      e) 240 m

Ans. b) 62.5m

62. A flywheel on a motor goes from rest to 1000 rpm in 6 sec. the number of revolution made is nearly equal to 

a) 25   b) 50    c) 100     d) 250      e)500

Ans. b) 50

63. Which of the following is not the unit of energy

a) kg m    b) kcal    c)wattr    d) watt hours    e) kg m x (m/sec)²

Ans. c) wattr

64. which of the following is the example of lever of first order

1. arm of man
2. pair of scissors
3. pair of clinical tongs
4. all of the above
5. none of the above

Ans. d) all of the above

65. A pair of smith’s tongs is an example of the lever of second order.

66. The angle which an inclined plane makes with the horizontal when a body placed on it is about to move down is known as angle of repose.

67. In actual machine, mechanical advantage is less than velocity ratio.

68. In ideal machine, mechanical advantage is equal to the velocity ratio.