Engineering Mechanics MCQ Questions and Answers in Civil Engineering

Question. The moment of inertia of a solid cone of mass m and base radius r about its vertical axis is
(a) 3mr2 / 5
(b) 3mr2 / 10
(c) 2mr2 / 5
(d) 4mr2 / 5

Answer : B

Question. The total momentum of a system of masses (i.e. moving bodies) in any one direction remains constant, unless acted upon by an external force in that direction. This statement is called
(a) Newton's first law of motion
(b) Newton's second law of motion
(c) principle of conservation of energy
(d) principle of conservation of momentum

Answer : D

Question. One joule is equal to
(a) 0.1 N - m
(b) 1 N - m
(c) 10 N - m
(d) 100 N - m

Answer : B

Question. When a body falls freely under gravitational force, it possesses
(a) no
(b) minimum
(c) maximum

Answer : A

Question. One kg force is equal to
(a) 7.8 N
(b) 8.9 N
(c) 9.8 N
(d) 12 N

Answer : C

Question. The unit of work in S.I. units is
(a) newton
(b) erg
(c) kg-m
(d) joule

Answer : D

Question. Varingon's theorem of moments states that if a number of coplaner forces acting on a particle are in equilibrium, then
(a) their algebraic sum is zero
(b) their lines of action are at equal distances
(c) the algebraic sum of their moments about any point in their plane is zero
(d) the algebraic sum of their moments about any point is equal to the moment of their resultant force about the same point

Answer : D

Question. The mechanical advantage of a lifting machine is the ratio of
(a) distance moved by effort to the distance moved by load
(b) load lifted to the effort applied
(c) output to the input
(d) all of the above

Answer : B

Question. The velocity ratio of a single purchase crab winch can be increased by
(a) increasing the length of the handle
(b) increasing the radius of the load drum
(c) increasing the number of teeth of the pinion
(d) all of the above

Answer : A

Question. The matter contained in a body, is called
(a) impulsive force
(b) mass
(c) weight
(d) momentum

Answer : B

Question. The algebraic sum of the resolved parts of a number of forces in a given direction is equal to the resolved part of their resultant in the same direction. This is known as
(a) principle of independence of forces
(b) principle of resolution of forces
(c) principle of transmissibility of forces
(d) none of these

Answer : B

Question. Static friction is always
(a) equal to
(b) less than
(c) greater than

Answer : C

Question. Moment of inertia of a triangular section of base (b) and height (h) about an axis passing through its C.G. and parallel to the base, is
(a) bh3 / 4
(b) bh3 / 8
(c) bh3 / 12
(d) bh3 / 36

Answer : D

Question. A lead ball with a certain velocity is made to strike a wall, it falls down, but rubber ball of same mass and with same velocity strikes the same wall, it rebounds. Select the correct reason from the following
(a) both the balls undergo an equal change in momentum
(b) the change in momentum suffered by rubber ball is more than the lead balf
(c) the change in momentum suffered by rubber ball is less than the lead ball
(d) none of the above

Answer : B

Question. If a given force (or a given system of forces) acting on a body
(a) change
(b) does not change

Answer : B

Question. The minimum force required to slide a body of weight W on a rough horizontal plane is
(a) W sin ?
(b) W cos ?
(c) W tan ?
(d) none of these

Answer : C

Question. Moment of inertia of a circular section about an axis perpendicular to the section is
(a) ?d3 / 16
(b) ?d3 / 32
(c) ?d4 / 32
(d) ?d4 / 64

Answer : C

Question. 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
(a) simple pendulum
(b) compound pendulum
(c) torsional pendulum
(d) second's pendulum

Answer : B

Question. The force required to move the body up the plane will be minimum if it makes an angle with the inclined plane
(a) equal to
(b) less than
(c) greater than

Answer : A

Question. The power developed by a body acted upon by a torque T newton metre (N - m) and revolving at ? radian / s is given by
(a) T.? (in watts)
(b) T.? / 60 (in watts)
(c) T.? / 75 (in kilowatts)
(d) T.? / 4500 (in kilowatts)

Answer : A

Question. The unit of moment of inertia of an area is
(a) kg-m2
(b) kg-m-s2
(c) kg/m2
(d) m4

Answer : D

Question. When a particle moves along a circular path, its acceleration has two components, one is normal component and the other is tangential component of acceleration
(a) True
(b) False

Answer : A

Question. A screw jack used for lifting the loads is
(a) a reversible machine
(b) a non-reversible machine
(c) an ideal machine
(d) none of these

Answer : B

Question. The moment of inertia of a solid sphere of mass m and radius r is
(a) 2mr2 / 3
(b) 2mr2 / 5
(c) mr2
(d) mr2 / 2

Answer : B

Question. A differential pulley block has larger and smaller diameters of 100 mm and 80 mm respectively. Its velocity ratio is
(a) 5
(b) 10
(c) 20
(d) 40

Answer : B

Question. The velocity ratio for the first system of pulleys is. Where n is the number of pulleys.
(a) n
(b) n2
(c) 2n
(d) 2n - 1

Answer : C

Question. The velocity of a particle moving with simple harmonic motion is
(a) zero
(b) minimum
(c) maximum

Answer : C

Question. The moment of a force
(a) is the turning effect produced by a force, on the body, on which it acts
(b) is equal to the product of force acting on the body and the perpendicular distance of a point and the line of action of the force
(c) is equal to twice the area of the triangle, whose base is the line representing the force and whose vertex is the point, about which the moment is taken
(d) all of the above

Answer : D

Question. Which of the following statement is correct?
(a) The kinetic egergy of a body during impact remains constant.
(b) The kinetic energy of a body before impact is equal to the kinetic energy of a body after impact.
(c) The kinetic energy of a body before impact is less than the kinetic energy of a body after impact.
(d) The kinetic energy of a body before impact is more than the kinetic energy of a body after impact.

Answer : D

109.Two like parallel forces are acting at a distance of 24 mm apart and their resultant is 20 N. If the line of action of the resultant is 6 mm from any given force the two forces are
(a) 15 N and 5 N
(b) 20 N and 5 N
(c) 15 N and 10 N
(d) none of these

Answer : A

Question. According to Newton's first law of motion,
(a) every body continues in its state of rest or of uniform motion, in a straight line, unless it is acted upon by some external force
(b) 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
(c) to every action, there is always an equal and opposite reaction
(d) none of the above

Answer : A

Question. The force applied on a body of mass 100 kg to produce an acceleration of 5 m/s2, is
(a) 20N
(b) 100N
(c) 500N
(d) none of these

Answer : C

Question. One watt is equal to
(a) 0.1 joule / s
(b) 1 joule / s
(c) 10 joules / s
(d) 100 joules / s

Answer : B

Question. Which of the following statement is wrong?
(a) A force acting in the opposite direction to the motion of the body is called force of friction.
(b) The ratio of the limiting friction to the normal reaction is called coefficient of friction.
(c) A machine whose efficiency is 100% is known as an ideal machine.
(d) The velocity ratio of a machine is the ratio of load lifted to the effort applied

Answer : D

Question. If tension in the cable supporting a lift moving downwards is half the tension when it is moving upwards, the acceleration of the lift is
(a) g / 2
(b) g / 3
(c) g / 4
(d) none of these

Answer : D

Question. In a single threaded worm and worm wheel, the number of teeth on the worm is 50. The diameter of the effort wheel is 100 mm and that of load drum is 50 mm. The velocity ratio is
(a) 50
(b) 100
(c) 150
(d) 200

Answer : B

Question. The velocity ratio of a first system of pulleys with 4 pulleys is
(a) 4
(b) 8
(c) 16
(d) 20

Answer : C

Question. The friction experienced by a body, when in motion, is known as
(a) rolling friction
(b) dynamic friction
(c) limiting friction
(d) static friction

Answer : B

Question. In a screw jack, the effort required to lift the load is given by. Where W = Load lifted, ? = Helix angle, and ? = Angle of friction
(a) P = W tan (? ? ?)
(b) P = W tan (? + ?)
(c) P = W tan (? - ?)
(d) P = W tan (? + ?)

Answer : B

Question. According to lami's theorem
(a) the three forces must be equal
(b) the three forces must be at 120? to each other
(c) the three forces must be in equilibrium
(d) if the three forces acting at a point are in equilibrium, then each force is proportional to the sine of the angle between the other two

Answer : D

Question. If the number of pulleys in a system is equal to its velocity ratio, then it is a
(a) first
(b) second
(c) third

Answer : B

Question. A weight of 1000 N can be lifted by an effort of 80 N. If the velocity ratio is 20, the machine is
(a) reversible
(b) non-reversible
(c) ideal

Answer : A

Question. The ratio of static friction to dynamic friction is always
(a) equal to one
(b) less than one
(c) greater than one
(d) none of these

Answer : C

Question. The length of a second's pendulum is
(a) 94.9 cm
(b) 99.4 cm
(c) 100 cm

Answer : B

Question. When a body of mass moment of inertia / (about a given axis) is rotated about that axis with an angular velocity ?, then the kinetic energy of rotation is
(a) I ?
(b) I ?2
(c) 0.5 I ?
(d) 0.5 I ?2

Answer : D

Question. The static friction
(a) bears a constant ratio to the normal reaction between the two surfaces
(b) is independent of the area of contact, between the two surfaces
(c) always acts in a direction, opposite to that in which the body tends to move
(d) all of the above

Answer : D

Question. The resultant of two forces P and Q (such that P > Q) acting along the same straight line, but in opposite direction, is given by
(a) P + Q
(b) P - Q
(c) P / Q
(d) Q / P

Answer : B

Question. In order to completely specify angular displacement by a vector, it must fix
(a) direction of the axis of rotation
(b) magnitude of angular displacement
(c) sense of angular displacement
(d) all of these

Answer : D

Question. Non-coplaner concurrent forces are those forces which
(a) meet at one point, but their lines of action do not lie on the same plane
(b) do not meet at one point and their lines of action do not lie on the same plane
(c) meet at one point and their lines of action also lie on the same plane
(d) do not meet at one point, but their lines of action lie on the same plane

Answer : A

Question. The maximum efficiency of a lifting machine is
(a) 1 / m
(b) V.R. / m
(c) m / V.R.
(d) 1 / m x V.R.

Answer : D

Question. The acceleration of a body sliding down an inclined surface is
(a) g sin ?
(b) g cos ?
(c) g tan ?
(d) none of these

Answer : A

Question. The term 'centroid' is
(a) the same as centre of gravity
(b) the point of suspension
(c) the point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis
(d) none of the above

Answer : A

Question. The forces, which meet at one point and their lines of action also lie on the same plane, are known as
(a) coplaner concurrent forces
(b) coplaner non-concurrent forces
(c) non-coplaner concurrent forces
(d) non-coplaner non-concurrent forces

Answer : A

Question. The centre of gravity a T-section 100 mm x 150 mm x 50 mm from its bottom is
(a) 50 mm
(b) 75 mm
(c) 87.5 mm
(d) 125 mm

Answer : C

Question. Joule is the unit of
(a) force
(b) work
(c) power
(d) energy

Answer : B

Question. Which of the following statement is correct?
(a) The algebraic sum of the forces, constituting the couple is zero.
(b) The algebraic sum of the forces, constituting the couple, about any point is the same.
(c) A couple cannot be balanced by a single force but can be balanced only by a couple of opposite sense
(d) all of the above

Answer : D

Question. Two forces are acting at an angle of 120?. The bigger force is 40N and the resultant is perpendicular to the smaller one. The smaller force is
(a) 20N
(b) 40N
(c) 40N
(d) none of these

Answer : A

Question. The potential energy of a vertically raised body is
(a) equal to
(b) less than
(c) greater than

Answer : A

Question. If the body falls freely under gravity, then the gravitational acceleration is taken as
(a) Plus 8.9 m/s2
(b) ? 8.9 m/s2
(c) Plus 9.8 m/s2
(d) ? 9.8 m/s2

Answer : C

Question. An ideal machine is one whose efficiency is
(a) between 60 to 70%
(b) between 70 to 80%
(c) between 80 to 90%
(d) 100%

Answer : D

Question. A machine having an efficiency greater than 50%, is known as
(a) reversible machine
(b) non-reversible machine
(c) neither reversible nor non-reversible machine
(d) ideal machine

Answer : A

Question. Moment of inertia of a circular section about its diameter (d) is
(a) ?d3 / 16
(b) ?d3 / 32
(c) ?d4 / 32
(d) ?d4 / 64

Answer : D

Question. Moment of inertia is the
(a) second moment of force
(b) second moment of area
(c) second moment of mass
(d) all of these

Answer : D

Question. Moment of inertia of a triangular section of base (b) and height (h) about an axis through its base, is
(a) bh3 / 4
(b) bh3 / 8
(c) bh3 / 12
(d) bh3 / 36

Answer : C

Question. The centre of gravity of an equilateral triangle with each side a, is
(a) ?3 a/2
(b) 2?3 a
(c) a/2 ?3
(d) 3?2 a

Answer : C

Question. A redundant frame is also called
(a) perfect
(b) imperfect
(c) deficient

Answer : B

Question. For any system of coplaner forces, the condition of equilibrium is that the
(a) algebraic sum of the horizontal components of all the forces should be zero
(b) algebraic sum of the vertical components of all the forces should be zero
(c) algebraic sum of moments of all the forces about any point should be zero
(d) all of the above

Answer : D

Question. The forces, whose lines of action are parallel to each other and act in the same directions, are known as
(a) coplaner concurrent forces
(b) coplaner non-concurrent forces
(c) like parallel forces
(d) unlike parallel forces

Answer : C

Question. A machine having an efficiency less than 50%, is known as
(a) reversible machine
(b) non-reversible machine
(c) neither reversible nor non-reversible machine
(d) ideal machine

Answer : B

Question. The friction experienced by a body, when at rest, is known as
(a) static friction
(b) dynamic friction
(c) limiting friction
(d) coefficient of friction

Answer : A

Question. The coefficient of restitution for inelastic bodies is
(a) zero
(b) one
(c) between zero and one
(d) more than one

Answer : A

Question. The maximum velocity of a particle moving with simple harmonic motion is
(a) ?
(b) ?r
(c) ?2r
(d) ?/r

Answer : B

Question. The efficiency of a lifting machine is the ratio of
(a) output to the input
(b) work done by the machine to the work done on the machine
(c) mechanical advantage to the velocity ratio
(d) all of the above

Answer : D

Question. The point, through which the whole weight of the body acts, irrespective of its position, is known as
(a) moment of inertia
(b) centre of gravity
(c) centre of percussion
(d) centre of mass

Answer : B