### Civil Engineering - Applied Mechanics MCQs Part 4

1. A retarding force on a body does not

A.
change the motion of the body
B.
retard the motion of the body
C.
introduce the motion of the body
D.
none of these.

2. The unit of force in C.G.S. system of units, is called

A.
dyne
B.
Newton
C.
kg
D.
all the above.

3. A block of weight 50 kg is placed on a horizontal plane. When a horizontal force of 18 kg is applied, the block is just on the point of motion. The angle of friction is

A.
17° 48'
B.
18° 48'
C.
19° 48'
D.
20° 48'
E.
21° 48'.

4. From a circular plate of a diameter 6 cm is cut out a circle whose diameter is equal to the radius of the plate. The C.G. of the remainder from the centre of circular plate is at a distance of

A.
2.0 cm
B.
1.5 cm
C.
1.0
D.
0.5 cm.

5. The force which produces an acceleration of 1 m/sec2 in a mass of one kg, is called

A.
dyne
B.
Netwon
C.
joule
D.
erg.

6. The units of inertia of mass, are

A. kg/m
B. kg/m2
C. m4
D. m3
E. kg-m2.

7. A sphere is resting on two planes BA and BC which are inclined at 45° and 60° respectively with the horizontal. The reaction on the plane BA will be

A. less than that on BC
B. more than that of BC
C. equal to that on BC
D. zero
E. none of these.

8. A projectile is fired at an angle θ to the vertical. Its horizontal range will be maximum when θ is

A. 0°
B. 30°
C. 45°
D. 60°
E. 90°.

9. 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 mechanical advantage of the lifting machine is

A. 15
B. 18
C. 20
D. 26.

10. The centre of gravity of a trapezoidal dam section whose top width is a, bottom width is b and the vertical side is a, from its vertical face is

A.
B.
C.
D. none of these.

11. One half of a vibration of a body, is called

A. period time
B. oscillation
C. beat
D. amplitude.

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

A. towards the wall at its upper end
B. away from the wall at its upper end
C. upwards at its upper end
D. downwards at its upper end
E. none of these.

13. The acceleration of a particle moving along the circumference of a circle with a uniform speed, is directed

B. tangentially at that point
C. away from the centre
D. towards the centre.

14. From the circular plate of a diameter 6 cm is cut out a circular plate whose diameter is equal to radius of the plate. The c.g. of the remainder shifts from the original position through

A. 0.25 cm
B. 0.50 cm
C. 0.75 cm
D. 1.00 cm.

15. If a particle moves with a uniform angular velocity ω radians/sec along the circumference of a circle of radius r, the equation for the velocity of the particle, is

A. v = ω
B. y = ω y - r
C. v = ω
D. v = ω

16. In simple harmonic motion, acceleration of a particle is proportional to

A. rate of change of velocity
B. displacement
C. velocity
D. direction
E. none of these.

17. A heavy ladder resting on a floor and against a vertical wall may not be in equilibrium, if

A. floor is smooth and the wall is rough
B. floor is rough and the wall is smooth
C. floor and wall both are smooth surfaces
D. floor and wall both are rough surfaces.

18. In a simple screw jack, the pitch of the screw is 9 mm and length of the handle operating the screw is 45 cm. The velocity ratio of the system is

A. 1.5
B. 5
C. 25
D. 314

19. To double the period of oscillation of a simple pendulum

A. the mass of its bob should be doubled
B. the mass of its bob should be quadrupled
C. its lenght should be quadrupled
D. its length should be doubled.

20. For a particle moving with a simple harrmonic motion, the frequency is

A. directly proportional to periodic time
B. inversely proportional to periodic time
C. inversely proportional to its angular velocity
D. directly proportional to its angular velocity
E. none of these.

21. According to Kennedy's theorem, if three bodies have plane motions, their instantaneous centres lie on

A. a point
B. a straight line
C. two straight lines
D. a triangle.

22. A ball of mass 250 g moving on a smooth horizontal table with a velocity of 10 m/sec hits an identical stationary ball B on the table. If the impact is perfectly plastic, the velocity of the ball B just after impact would be

A. zero
B. 5 m/sec
C. 10 m/sec
D. none of these.

23. If α is the angular acceleration of a compound pendulum whose angular displace ment is θ, the frequency of the motion is

A. 2πα/θ
B.
C. 4πα/θ
D. 2πα - θ.

24. If two forces each equal to T in magnitude act at right angles, their effect may be neutralised by a third force acting along their bisector in opposite direction whose magnitude will be

A. 2 T
B. 1/2 T
C. 2 T
D. 3 T
E. none of these.

25. Energy may be defined as

A. power of doing work
B. capacity of doing work
C. rate of doing work
D. all the above.

26. The intrinsic equation of catenary is

A. S = c tan ψ
B. y = c cosh x/c
C. y = c cosh ψ
D. y = c sinh ψ.

27. A ball which is thrown upwards, returns to the ground describing a parabolic path during its flight

A. vertical component of velocity remains constant
B. horizontal component of velocity remains constant
C. speed of the ball remains constant
D. kinetic energy of the ball remains constant.

28. Angular acceleration of a particle may be expressed as

B. degrees/sec2
C. revolutions/sec
D. all the above.

29. Two loads of 50 kg and 75 kg are hung at the ends of a rope passing over a smooth pulley shown in below figure. The tension in the string is :

A. 50 kg
B. 75 kg
C. 25 kg
D. 60 kg.

30. Total no of instantaneous centres of a machine having n links, is

A. n/2
B. n
C. (n - 1)
D.

31. A weight of 100 kg is supported by a string whose ends are attached to pegs A and B at the same level shown in below figure. The tension in the string is

A. 50 kg
B. 75 kg
C. 100 kg
D. 120 kg.

32. A train weighing 196 tonnes experiences a frictional resistance of per tonne. The speed of the train at the top of a down gradient 1 in 78.4 is 36 km/hour. The speed of the train after running 1 km down the slope, is

A. 510 m/sec
B. 105 m/sec
C. 53 m/sec
D. 35 m/sec.

33. The reaction at the support B of the beam shown in below figure is

A. 1.6 t
B. 9.6 t
C. 8.5 t
D. 0.5 t.

34. A stone is whirled in a vertical circle, the tension in the string, is maximum

A. when the string is horizontal
B. when the stone is at the highest position
C. when the stone is at the lowest position
D. at all the positions.

35. If the velocity of projection is 4 m/sec and the angle of projection is α°, the maximum height of the projectile from a horizontal plane, is

A.
B.
C.
D.

36. If a spherical body is symmetrical about its perpendicular axes, the moment of inertia of the body about an axis passing through its centre of gravity as given by Routh's rule is obtained by dividing the product of the mass and the sum of the squares of two semi-axes by n where n is

A. 2
B. 3
C. 4
D. 5.

37. The angle of projection for a range is equal to the distance through which the particle would have fallen in order to acquire a velocity equal to the velocity of projection, will be

A. 30°
B. 45°
C. 60°
D. 75°.

38. A particle executes a simple harmonic motion. While passing through the mean position, the particle possesses

A. maximum kinetic energy and minimum potential energy
B. maximum kinetic energy and maximum potential energy
C. minimum kinetic energy and maximum potential energy
D. minimum kinetic, energy and minimum potential energy
E. none of these.

39. A body of weight w placed on an inclined plane is acted upon by a force P parallel to the plane which causes the body just to move up the plane. If the angle of inclination of the plane is θ and angle of friction is φ, the minimum value of P, is

A.
B.
C.
D.

40. Varigon's theorem of moments states

A. arithmetical sum of the moments of two forces about any point, is equal to the moments of their resultant about that point
B. algebraic sum of the moments of two forces about any point, is equal to the moment of their resultant about that point
C. arithmetical sum of the moments of the forces about any point in their plane, is equal to the moment of their resultant about that point
D. algebraic sum of the moments of the forces about any point in their plane, is equal to the moment of their resulant about that point.

41. If the angle of projection is double the angle of inclination (α) of the plane on which particle is projected, the ratio of times of fligh up the inclined plane and down the inclined plane, will be

A.
B.
C.
D. 2 cos α.

42. A smooth cylinder lying on its convex surface remains

A. in stable equilibrium
B. in unstable equilibrium
C. in neutral equilibrium
D. out of equilibrium
E. none of these.

43. A weight W is suspended at the free end of a light member hinged to a vertical wall. If the angle of inclination of the member with the upper wall is θ°, the force introduced in the member, is

A. W sec θ
B. W cos θ
C. W sin θ
D. W cosec θ
E. W tan θ.

44. A satellite goes on moving along its orbit round the earth due to

A. gravitational force
B. centrifugal force
C. centripital force
D. none of these.

45. The phenomenon of collision of two elastic bodies takes place because bodies

A. immediately after collision come momentarily to rest
B. tend to compress each other till they are compressed maximum possible
C. attempt to regain its original shape due to their elasticities
D. all the above.

46. A glass ball is shot to hit a wall from a point on a smooth floor. If the ball returns back to the point of projection in twice the time taken in reaching the wall, the coefficient of restitution between the glass ball and the wall is

A. 0.25
B. 0.33
C. 0.40
D. 0.50
E. 0.55

47. In case of S.H.M. the period of oscillation(T), is given by

A.
B.
C.
D.

48. Kinetic friction may be defined as

A. friction force acting when the body is just about to move
B. friction force acting when the body is in motion
C. angle between normal reaction and resultant of normal reaction and limiting friction
D. ratio of limiting friction and normal reaction.

49. If α and u are angle of projection and initial velocity of a projectile respectively, the total time of flight, is given by

A.
B.
C.
D.

50. ω rad/sec is the angular velocity of a crank whose radius is r. If it makes θ° with inner dead centre and obliquity of the connecting rod l is φ, the velocity v of the piston, is given by the equation

A. ω2(l cos φ + r sin φ tan θ)
B. ω2(l sin φ + r cos φ tan θ)
C. ω(l sin φ + r cos φ tan θ)
D. ω2(l sin φ - r cos θ tan φ).