# Engineering Mechanics - Mechanical Engineering test questions

## Engineering Mechanics - Mechanical Engineering test questions

1) The resultant of two forces P and Q acting at an angle is

a) √P2 + Q2 + PQcosΘ
b) √P2 - Q2 + PQcosΘ
c) √P2 + Q2 + 2PQcosΘ
d) √P2 + Q2 - PQcosΘ

ANSWER: c) √P2 + Q2 + 2PQcosΘ

2) A free body diagram of a body shows a body

a) Isolated from all external actions.
b) Isolated from its surroundings and all external actions on it.
c) With its surroundings and external forces acting on it.
d) None of these.

ANSWER: b) Isolated from its surroundings and all external actions on it.

3) ‘The algebraic sum of the moments of two forces about any point in their plane is equal to the moment of their

resultant about that point’. The above statement is called

a) Varignon’s theorem.
b) Principles of moments.
c) Theorem of parallel axes.
d) Theorem of perpendicular axes.

4) The angle of repose (α) holds the following relation with the angle of friction (Φ) in the condition

of limiting equilibrium.

a) α= Φ
b) α=2 Φ
c) α= Φ2
d) α= Φ/2

5) In a screw jack the effort (P) required to lift the load (W) is given by the relation

a) P=W tan (α- Φ)
b) P=W tan (α+ Φ)
c) P=W tan (α2+ Φ)
d) P=W tan (α 2- Φ)

ANSWER: b) P=W tan (α+ Φ)

6) The condition for maximum efficiency in case of a screw is given by

a) α = 45° + (Φ/2)
b) α = 45° - (Φ/2)
c) α = 60° + (Φ/2)
d) α = 60° - (Φ/2)

ANSWER: b) α = 45° - (Φ/2)

7) Time of flight of a projectile is given by

a) u sinα/g
b) u2 sinα/g
c) 2u sinα/g
d) 2u sin2α/g

8) Range of a projectile is given by

a) u2 sin2(α)/g
b) u2 sin (2α)/g
c) u3 sin (α)/g
d) u sin2 (α)/2g

9) Equation of a trajectory is written as

a) y = x tan a - gx2/2u2cos2α
b) y = x tan a + gx2/2u2cos2α
c) y = x2 tan α - gx2/2u2cos2α
d) y = x cos α gx2/2u2cos2α

ANSWER: a) y = x tan a - gx2/2u2cos2α

10) In a combined motion of translation and rotation

a) The motion of rotation takes place before the motion of translation.
b) The motion of translation takes place before the motion of rotation.
c) Both the motions take place simultaneously.
d) None of these.

ANSWER: c) Both the motions take place simultaneously.

11) In case of motion of two bodies (W1 > W2) connected by a string passing over a smooth pulley, the tension (T)

in the string is given by

a) W1 W2/ W1 + W2
b) 2W1 W2/ W1 + W2
c) 3W1 W2/ W1 + W2
d) 4W1 W2/ W1 + W2

ANSWER: b) 2W1 W2/ W1 + W2

12) After compression, the time taken by the bodies to regain original shape is known as

a) Time of compression.
b) Time of restitution.
c) Time of collision.
d) None of these.

13) When the distance between the shaft centres is …………………belts and ropes are used.

a) Large.
b) Small.
c) Very small.
d) None of these.

14) In cross belt drives the power is transmitted between pulleys rotating in

a) Opposite direction.
b) Same direction.
c) Either of these.
d) None of these.

15) Number of teeth on a wheel per unit of its pitch diameter is called

a) Circular pitch.
b) Module.
c) Diametral pitch.
d) None of these.

16) In a simple gear train, the motion of driven gear will ……………….if the number of idle gear is odd

a) Depend upon the number of teeth on the driving gear
b) Be same as that of driving gear
c) Be opposite as that of driving gear
d) None of these.

ANSWER: b) Be same as that of driving gear

17) The co-efficient of friction between two surfaces is the constant of proportionality between the applied

tangential force and the normal reaction at

a) Any instant when the body is at rest.
b) The instant of the application of the force.
c) The instant of impending motion.
d) Any instant after the motion takes place.

ANSWER: c) The instant of impending motion.

18) The co-efficient of restitution is defined on the basis of which parameters?

a) Velocity components along the line of impact only.
b) Velocity vectors before and after the impact.
c) Velocity components normal to the line of impact.
d) All of these.

ANSWER: a) Velocity components along the line of impact only.

19) What is the acceleration of the lift, when the tension in the cable supporting a lift moving upwards is twice

the tension when the lift moves downwards?

a) g
b) g/2
c) g/3
d) g/4

20) The length of a second pendulum is

a) 994mm
b) 550mm
c) 750mm
d) 1114mm

21) The centre of percussion is

a) It is the same as centre of gravity.
b) It is the point in a body about which it can rotate horizontally and oscillate under the influence of gravity.
c) It is the point of application of resultant of all forces tending to cause the body to rotate about a central

axis.
d) It is the point of suspension of a system.

ANSWER: c) It is the point of application of resultant of all forces tending to cause the body to rotate

22) Which among the following statement is correct?

a) Remains unchanged with variation in mass of the body.
b) Increases with increase of its mass.
c) Varies as the square of change in mass of body.
d) Decreases with increase of its mass.

ANSWER: a) Remains unchanged with variation in mass of the body.

23) What is the ratio of escape velocity on earth’s surface and it’s orbital velocity

a) 1/ √2
b) 1/2 √2
c) √2
d) 2√2

24) The moment of inertia of an area is always least with respect to

a) Vertical axis.
c) Centroidal axis.
d) None of these.

25) Crank of an engine rotates at 6 π radians/second. If the crank radius is 0.2 m, what is the maximum velocity

of the piston?

a) 1.2 π m/s
b) 3.6 π m/s
c) 2.4 π m/s
d) None of these.

26) Which among the following is a correct statement regarding ‘frequency of a vibrating string’?

a) It is inversely proportional to the diameter of the string.
b) It is inversely proportional to the square root of the mass parameter for unit length.
c) It is directly proportional to the square root of the mass per unit length.
d) None of these.

ANSWER: b) It is inversely proportional to the square root of the mass parameter for unit

length.

27) Coulomb friction is

a) The friction between bodies having relative motion
b) The friction between solids and liquids
c) The friction between two dry surface
d) None of these

ANSWER: a) The friction between bodies having relative motion

28) The moment of inertia of a body does not depend on

a) Mass of the body.
b) Distribution of mass in the body.
c) Angular velocity of the body.
d) All of these.

ANSWER: c) Angular velocity of the body.

29) A zero torque acting on a system will result in

a) Conservation of angular velocity.
b) Conservation of moment of momentum.
c) Conservation of linear velocity.
d) Conservation of angular momentum.

ANSWER: d) Conservation of angular momentum.

30) During planetary motion ………………….remains constant.

a) Total angular momentum.
b) Linear velocity
c) Angular speed
d) Angular acceleration