About Applied Mechanics

Following are some of the multiple choice questions on the Applied Mechanics with answers that will help the students in developing their knowledge.

Applied Mechanics MCQ

1. Joule is the unit of

  • work
  • force
  • power
  • torque
  • E. none of these.

2. One Joule is equivalent to

  • 9.81 Newton metre
  • 1 Newton metre
  • 1 kg wt metre
  • 1 dyne metre

3. One Newton is equivalent to

  • 1 kg. wt
  • 9.81 kg. wt
  • 981 dyne
  • 1/9.81 kg. wt

4. The tension in a cable supporting a lift

  • is more when the lift is moving downwards
  • is less when the lift is moving upwards
  • remains constant whether its moves downwards or upwards
  • is less when the lift is moving downwards.

5. Effect of a force on a body depends upon its

  • Direction
  • Magnitude
  • Position
  • All the above

6. The motion of a bicycle wheel is

  • Translatory
  • Rotary
  • Rotary and translatory
  • Curvilinear

7. Work may be defined as

  • force x distance
  • force x velocity
  • force x acceleration
  • none of these.

8. The force polygon representing a set of forces in equilibrium is a

  • Triangle
  • Open polygon
  • Closed polygon
  • Parallelogram

9. On a ladder resisting on a smooth ground and leaning against a rough vertical wall, the force of friction acts

  • Towards the wall at its upper end
  • Away from the wall at its upper end
  • Upwards at its upper end
  • Downwards at its upper end

10. A load of 500 kg was lifted through a distance of 13 cm. by an effort of 25 kg which moved through a distance of 650 cm. The efficiency of the lifting machine is

  • 50%
  • 40%
  • 55%
  • 30%.

11. A square hole is punched out of a circular lamina, the diagonal of the square being the radius of the circle. If r is the radius of the circle, the C.G. of the remainder from the corner of the square on the circumference will be

12. Pick up the correct statement from the following. The kinetic energy of a body

  • Before impact is equal to that after impact
  • Before impact is less than that after impact
  • Before impact is more than that after impact
  • Remain constant

13. The vertical reaction at the support ‘A’ of the structure shown in below figure, is

  • 1 t
  • 2 t
  • 3 t
  • 3.5 t

14. In which of the following trusses, the method of substitution is required for determining the forces in all the members of the truss by graphic statics?

  • Howe truss
  • King post truss
  • Fink truss
  • Warren truss

15. The centre of gravity of the trapezium as shown in below figure from the side is at a distance of

  • (h/3) × [(b + 2a)/(b + a)]
  • (h/3) × [(2b + a)/(b + a)]
  • (h/2) × [(b + 2a)/(b + a)]
  • (h/2) × [(2b + a)/(b + a)]

16. The member which does not carry zero force in the structure shown in below figure, is

  • ED
  • DC
  • BC
  • BD

17. A cable loaded with 0.5 tonne per horizontal metre span is stretched between supports in the same horizontal line 400 m apart. If central dip is 20 m, the minimum tension in the cable, will be

  • 200 tonnes at the centre
  • 500 tonnes at the centre
  • 200 tonnes at the right support
  • 200 tonnes at the left support.

18. Time period and length of a second’s pendulum respectively are

  • 1 sec and 99.4 cm
  • 1 sec and 92.7 cm
  • 2 sec and 99.4 cm
  • 2 sec and 92.7 cm

19. The angles between two forces to make their resultant a minimum and a maximum respectively are

  • 0° and 90°
  • 180° and 90°
  • 90° and 180°
  • 180° and 0°

20. The Law of Polygon of Forces states that

  • if a polygen representing the forces acting at point in a body is closed, the forces are in equilibrium
  • if forces acting on a point can be represented in magnitde and direction by the sides of a polygon taken in order, then the resultant of the forces will be represented in magnitude and direction by the closing side of the polygon
  • if forces acting on a point can be represented of a polygon taken in order, their sides of a polygon taken in order, their resultant will be represented in magnitude and direction by the closing side of the polygon, taken in opposite order
  • if forces acting on a point can be represented in magnitude and direction by the sides of a polygon in order, the forces are in equilibrium.

21. A system of coplanar forces is in equilibrium when

  • Force polygon closes
  • Funicular polygon closes
  • Both force polygon" and funicular polygon close
  • All the forces are concurrent

22. Minimum pull in a suspended cable with supports at two ends is equal to

  • Horizontal thrust
  • Support reactions
  • Resultant of horizontal thrust and support reaction
  • Half the weight of the cable

23. The following statement is one of the laws of Dynamic friction

  • The force of friction always acts in a direction opposite to that in which a body is moving
  • The magnitude of the kinetic friction bears a constant ratio to the normal reaction between two surfaces. The ratio being slightly less than that in the case of limiting friction
  • For moderate speeds the force of friction remains constant but decreases slightly with the increase of speed
  • All the above

24. The dimensions of Gravitational Universal constant ‘G’ are

  • M-1L2r2
  • M-1L3r2
  • M-2L3T2
  • M1L3T2

25. The centre of gravity of a quadrant of a circle lies along its central radius at a distance of

  • 0.2 R
  • 0.4 R
  • 0.3 R
  • 0.6 R

26. If a particle is projected inside a horizontal tunnel which is 554 cm high with a velocity of 60 m per sec, the angle of projection for maximum range, is

  • 10°
  • 11°
  • E. 12°.

27. A uniform rod 9 m long weighing 40 kg is pivoted at a point 2 m from one end where a weight of 120 kg is suspended. The required force acting at the end in a direction perpendicular to rod to keep it equilibrium, at an inclination 60° with horizontal, is

  • 40 kg
  • 60 kg
  • 10 kg
  • 100 kg.

28. The C.G. of a right circular cone lies on its axis of symmetry at a height of

  • h/2
  • h/3
  • h/4
  • h/5
  • E. h/6.

29. The c.g. of a thin hollow cone of height h, above its base lies on the axis, at a height of

30. U1 and u2 are the velocities of approach of two moving bodies in the same direction and their corresponding velocities of separation are v1 and v2. As per Newton's law of collision of elastic bodies, the coefficient of restitution (e) is given by

31. Maximum efficiency of a screw jack for the angle of friction φ, is

32. The resultant of two forces P and Q acting at an angle θ, is

  • P2 + Q2 + 2P sin θ
  • P2 + Q2 + 2PQ cos θ
  • P2 + Q2 + 2PQ tan θ
  • E.

33. The mechanical advantage of an ideal machine is 100. For moving the local through 2 m, the effort moves through

  • 0.02 m
  • 2 m
  • 2.5 m
  • 20 m.

34. When a body in equilibrium undergoes an infinitely small displacement, work imagined to be done, is known as

  • imaginary work
  • negative work
  • virtual work
  • none of these.

35. If three rigid rods are hinged together to form a triangle and are given rotary as well as translatory motion, the number of instantaneous centres of the triangle, will be

  • 1
  • 2
  • 3
  • 4
  • E. 5.

36. If a body moves in such a way that its velocity increases by equal amount in equal intervals of time, it is said to be moving with

  • a uniform retardation
  • a uniform acceleration
  • a variable acceleration
  • a variable retardation
  • E. none of these.

37. The unit of Moment of Inertia of a body, is

  • m
  • m2
  • m3
  • m4
  • E. none of these.

38. A projectile is thrown at an angle a to the horizontal with α velocity v. It will have the maximum centripetal acceleration

  • at the start
  • at the top of the trajectory
  • as it strikes the ground
  • else where.

39. The locus of the instantaneous centre of a moving rigid body, is

  • straight line
  • involute
  • centroid
  • spiral.

40. The equation of motion of a particle starting from rest along a straight line is x = t3 - 3t2 + 5. The ratio of the accelerations after 5 sec and 3 sec will be

  • 2
  • 3
  • 4
  • 5

41. At a given instant ship A is travelling at 6 km/h due east and ship B is travelling at 8 km/h due north. The velocity of B relative to A is

  • 7 km/hrs
  • 2 km/hrs
  • 1 km/hrs
  • 10 km/hrs
  • E. 14 km/hrs.

42. The forces which meet at one point and have their lines of action in different planes are called

  • coplaner non-concurrent forces
  • non-coplaner concurrent forces
  • non-coplaner non-current forces
  • intersecting forces
  • E. none of these.

43. The centre of gravity of a triangle is at the point where three

  • medians of the triangle meet
  • perpendicular bisectors of the sides of the triangle meet
  • bisectors of the angle of the triangle meet
  • none of these.

44. A hoop of radius 3 m weighs 100 kg. It rolls along a horizontal floor so that at its centre of mass has a speed of 200 mm/sec. The work required to stop the hoop is

  • 2 J
  • 4 J
  • 6 J
  • 8 J

45. The following is not a law of static friction:

  • The force of friction always acts in a direction opposite to that in which the body tends to move
  • The force of friction is dependent upon the area of contact
  • The force of friction depends upon the roughness of the surface
  • The magnitude of the limiting friction bears a constant ratio to the normal reaction between two surfaces

46. M.I. of solid sphere, is

  • ⅔ Mr²
  • ½ Mr²
  • Mr²
  • πr4/2

47. The motion of a particle is described by the relation x = t²- 10t + 30, where x is in meters and t in seconds. The total distance travelled by the particle from t = 0 to t = 10 seconds would be

  • Zero
  • 30 m
  • 50 m
  • 60 m

48. Two forces act an angle of 120°. If the greater force is 50 kg and their resultant is perpendicular to the smaller force, the smaller force is

  • 20 kg
  • 25 kg
  • 30 kg
  • 35 kg

49. When a circular wheel rolls on a straight track, then the shape of body centrode and space centrode respectively are

  • Straight line and parabola
  • Straight line and circle
  • Circle and straight line
  • Circle and parabola

50. A cable loaded with 10 kN/m of span is stretched between supports in the same horizontal line 100 m apart. If the central dip is 10 m, then the maximum and minimum pull in the cable respectively are

  • 1346.3 kN and 1500 kN
  • 1436.2 kN and 1250 kN
  • 1346.3 kN and 1250 kN
  • 1436.2 kN and 1500 kN

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