# Theory of Machines - Mechanical Engineering test

## Theory of Machines - Mechanical Engineering test

1) When a body is subjected to transverse vibrations ………………stress is induced in the body

a) Shear
b) Tensile
c) Compressive
d) None of these

2) What is the arc of contact when in an involute tooth profile the pressure angle is 20° and path of contact is 45 mm?

a) 32.65mm
b) 27.89mm
c) 47.89mm
d) 12.5mm

3) The effect of gyroscopic couple, acting on a ship pitching upward will be to

a) Move the ship towards port
b) Move the ship towards star board
c) Roll the ship slightly in clockwise direction when viewed from the stern
d) None of these

ANSWER: b) Move the ship towards star board

4) There will be ……………..in case of a shaft carrying three rotors at its ends

a) Three nodes
b) Two nodes
c) One node
d) None of these

5) A rigid body under the action of external forces can be replaced by two masses placed at a fixed distance apart. The two masses form an equivalent dynamical system, if

a) The sum of mass movement of inertia of masses about their centre of gravity is equal to the mass moment of inertia of the body
b) The sum of two masses is equal to the total mass of the body
c) The centre of gravity of the two masses coincides with that of the body.
d) All of these.

6) The suitable bearing for fluctuating loads is

a) Needle-roller bearing
b) Ball bearing
c) Roller bearing
d) Sleeve bearing

7) Automobile steering gear is an example of …………….pair

a) Sliding
b) Lower
c) Turning
d) Rotary

8) In case of a cam, the maximum value of the pressure angle is kept as

a) 30°
b) 20°
c) 15°
d) 45°

9) The angle of contact taken into consideration should be of ………………when two pulleys of different diameters are connected by means of an open belt drive

a) The larger pulley
b) The smaller pulley
c) The average of two pulleys
d) None of these

10) The relation between the number of pairs forming a kinematic chain and the number of links is Where, l = number of links and p = number of pairs

a) l=p – 1
b) l=2p – 3
c) l=2p – 2
d) l=2p – 4

11) The power of porter governor is

a) Inversely proportional to speed
b) Inversely proportional to (speed)2
c) Proportional to (speed)2
d) Independent of speed

ANSWER: b) Inversely proportional to (speed)2

12) The effort (P) required to lift the load (W) in a screw jack (where a is the helix angle and f is the angle of friction), is given by

a) P = W cos (α + Φ)
b) P = W sin (α + Φ)
c) P = W tan (α - Φ)
d) P = W tan (α + Φ)

ANSWER: d) P = W tan (α + Φ)

13) In a locomotive, the ratio of the connecting rod length to the crank radius is kept very large to

a) Minimise the effect of secondary forces
b) Minimise the effect of primary forces
c) Have perfect balancing
d) None of these

ANSWER: a) Minimise the effect of secondary forces

14) Critical damping is a function of

a) Stiffness and natural frequency
b) Stiffness and damping coefficient
c) Mass and stiffness
d) Mass and damping co-efficient

15) What is the rate of decay of oscillations known as?

a) Critical damping
b) Logarithmic decrement
c) Damping co-efficient
d) Transmissibility

16) Dedendum circle diameter is equal to

a) Length of arc of contact x cosΦ
b) Pitch circle diameter x cosΦ
c) Base circle diameter x cosΦ
d) Addendum circle diameter x cosΦ

ANSWER: b) Pitch circle diameter x cosΦ

17) What will be the maximum efficiency of a screw jack having square threads and friction angle 30°?

a) 66.66%
b) 33.33%
c) 25%
d) 30%

18) Which among the following is the inversion of slider crank chain mechanism?

a) Whit-worth quick return mechanism
b) Hand pump
c) Oscillating cylinder engine
d) All of these

19) In a kinematic chain, a quaternary joint is equivalent to

a) One binary point
b) Two binary point
c) Three binary point
d) None of these

20) In case of a mechanism having plane motion, the Grubler’s criterion for determining the degrees of freedom (n) is

a) n = 3 (l – 1) – 2j
b) n = 2 (l – 1) –j
c) n = 4 (l – 1) – 2j
d) none of these

ANSWER: a) n = 3 (l – 1) – 2j

21) Klein’s construction is mainly used

a) To determine linear velocity and acceleration of piston
b) To determine angular velocity of the connecting rod
c) To determine piston displacement
d) To determine angular acceleration of crank

ANSWER: a) To determine linear velocity and acceleration of piston

22) Regarding a ‘reverted gear train’, which of the following statements is correct?

a) The axes of the first and the last gear are co-axial
b) At least one of the gear axis is in motion
c) The axes of the first and the last gear are parallel
d) None of these

ANSWER: a) The axes of the first and the last gear are co-axial

23) A lift screw will be self-locking if Where α = helix angle of threads and Φ = angle of friction

a) α = Φ
b) α > Φ
c) α < Φ
d) none of these

24) The velocity diagram is …………….when the follower moves with S.H.M

a) Parabolic
b) Hyperbolic
c) Sinusoidal
d) Cosine curve

25) The principle of direct and reverse cranks is readily applicable to the problems of balancing of

a) In-lines engines
b) Coupled locomotives
c) Rotors

26) How many degrees of freedom does an epicylic gear have?

a) One
b) Two
c) Three
d) Four

27) The train value of a gear train is

a) equal to velocity ratio of a gear train
b) always greater than unity
c) always less than unity
d) reciprocal of velocity ratio of a gear train

ANSWER: d) reciprocal of velocity ratio of a gear train

28) When the speed is high and the viscous force is small, which of the following dynamometers is used for power measurement?

a) Tesla fluid friction dynamometer
b) Froude water vortex dynamometer
c) Belt transmission dynamometer
d) Rope brake dynamometer

ANSWER: a) Tesla fluid friction dynamometer

29) In a locomotive, the ratio of connecting rod length to crank radius kept very high

a) To achieve perfect balancing
b) To minimise the effect of primary forces
c) To minimise the effect of secondary forces
d) All of these

ANSWER: c) To minimise the effect of secondary forces

30) Which of the following statement is correct regarding ‘involute profile of gear tooth’?

a) Wear is less, as there are two convert surfaces in contact
b) The velocity ratio is not affected if there is a little variation in centre distance
c) There is variation in pressure angle throughout engagement
d) All of these

ANSWER: b) The velocity ratio is not affected if there is a little variation in centre distance

31) In a radial cam with a roller on follower, the prime circle can be defined as

a) The smallest circle tangent to the cam profile
b) The smallest circle tangent to the pitch curve
c) A circle drawn with radius equal to the distance between the pitch point and the centre of base circle
d) None of these

ANSWER: b) The smallest circle tangent to the pitch curve

32) With which of the following followers, surface stresses are minimum in a cam-follower arrangement?

a) Roller follower
b) Mushroom follower with flat face
c) Knife edge follower
d) Mushroom follower with spherical face

ANSWER: d) Mushroom follower with spherical face

33) Tumbler gears are

a) bevel gears having the same module
b) gears in lathe machine used for reversing the direction of rotation of driven gears
c) pairs of gears in a machine that serve to connect the dividing head with table movement
d) None of these

ANSWER: b) gears in lathe machine used for reversing the direction of rotation of driven gears

34) Bifilar suspension method is used to

a) determine moment of inertia
b) determine centripetal acceleration
c) determine natural frequency of vibration
d) All of these

ANSWER: a) determine moment of inertia

35) The frequency of damped vibrations as compared to frequency of undamped vibrations, with viscous damping, is

a) Zero
b) Less
c) More
d) Same

36) Sensitivity of governor is the ratio of

a) Range of speed to the mean speed
b) Maximum speed to the minimum speed
c) Mean speed to the range of speed
d) Governor lift to the range of speed

ANSWER: a) Range of speed to the mean speed

37) Corioli’s component of acceleration will exist only if

a) The two coincidental points have relative angular velocity of sliding
b) The two coincidental points must have same centre of rotation
c) There are two coincidental points
d) The two coincidental points have linear relative velocity of sliding accompanied by the rotation about fixed centres

ANSWER: d) The two coincidental points have linear relative velocity of sliding accompanied by the rotation about fixed centres

38) In case of gears, when does interference take place?

a) When gears do not move smoothly in absence of lubrication
b) When the gear teeth are undercut
c) Whenever the forms of the mating teeth are such that contact between them can occur at some place other than along the correct path of contact
d) When the pitch of the gears is not same

ANSWER: c) Whenever the forms of the mating teeth are such that contact between them can occur at some place other than along the correct path of contact

39) Which of the following factors affect the critical speed of a shaft?

a) Diameter of the disc
b) Eccentricity
c) Span of the shaft
d) All of these.