# 140+ Theory of Mechanics Solved MCQs

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1.

## The uniform wear conditions are used_____.

A. for maximum power to be transmitted
B. for safe design of clutches
C. for safe design bearing
D. for overcoming the frictional torque
Answer» B. for safe design of clutches
2.

## The uniform Pressure conditions are used_____.

A. for maximum power to be transmitted
B. for safe design of clutches
C. for safe design bearing
D. for overcoming the frictional torque
Answer» C. for safe design bearing
3.

## For safe design of bearing, we assume____.

A. maximum power to be transmitted
B. safe design of clutches
C. safe design bearing
D. overcoming the frictional torque
Answer» A. maximum power to be transmitted
4.

## For safe design of clutches, we assume____.

A. uniform pressure conditions
B. uniform wear condition
C. neither uniform pressure nor uniform wear
D. all of the above
5.

A. p.w=constant
B. p.r=constant
C. p.w=constant
D. p.t=constant
6.

A. r
B. (1/2).r
C. (3/2).r
D. (2/3)r
7.

A. r
B. (1/2).r
C. (3/2).r
D. (2/3).r
8.

A. >1
B. 1
C. <1
D. (1/2)
9.

## Torque required to overcome the friction between shaft and bearing surface in case of multiple flat collar bearing is ___________.

A. independent on of collars
B. dependent on radius of collar
C. dependent of no of collars
D. none of above
Answer» A. independent on of collars
10.

## In case of flat pivot bearing,the rubbing velocity is _________.

A. maximum at the center of the contact area
B. zero at the center and maximum at the outer radius
C. uniform throughout the contact area
D. zero at the outer radius
Answer» B. zero at the center and maximum at the outer radius
11.

## The rate of wearing in case of flat pivot bearing is ______.

A. inversely proportional to the pressure intensity
B. directly proportional to the rubbing velocity
C. directly proportionl to the pressure intensity
D. both (b) and (c )
Answer» D. both (b) and (c )
12.

## For calculating the friction power for bearing, the assumptions made in practice are_____.

A. the rate of wearing at the surface is uniform
B. the rubbing velocity is constant
C. the pressure intensity is uniform
D. (a) and (c ) only
Answer» D. (a) and (c ) only
13.

## In case of flat pivot bearing the frictional torque transmitted for uniform pressure as compared to the frictional torque transmitted for uniform wear_____.

A. is more
B. is less
C. is constant
D. may be more or less
14.

A. (1/3)
B. (2/3)
C. 1
D. (4/3)
15.

## When the axial load carried by the shaft in case of flat collar bearing, is large; a number of collars are provided on the shaft. This is done____.

A. to reduce the frictional torque
B. to increase the frictional torque
C. to reduce the intensity of pressure
D. to increse the intensity of pressure
Answer» C. to reduce the intensity of pressure
16.

## Choose the correct statement regarding the safe design of a bearing.

A. when horse power lost in friction is to be determined, uniform rate of wear is assumed
B. when horse power transmitted is to be determined, uniform pressure is assumed
C. when horse power lost in friction is to be determined, uniform pressure is assumed and when horse power transmitted is to be determined, uniform wear is assumed
D. none of the above
Answer» C. when horse power lost in friction is to be determined, uniform pressure is assumed and when horse power transmitted is to be determined, uniform wear is assumed
17.

A. 1.33
B. 1
C. sinϴ
D. cosϴ
18.

A. 1.33
B. 1
C. sinϴ
D. cosϴ
19.

A. sinϴ
B. cosϴ
C. tanϴ
D. 1/sinϴ
20.

A. (2/3)
B. (3/2)
C. (4/3)
D. (3/4)
21.

A. (3/4)
B. (4/3)
C. (2/3)
D. 1
22.

## The frictional torque for the same diameter in a conical bearing is ____.

A. more
B. less
C. equal
D. may be more or less
23.

## The frictional torque transmitted by a conical bearing is ____.

A. less than that of flat collar bearing
B. equal to that of flat collar bearing
C. more than that of flat collar bearing
D. none of the above
Answer» C. more than that of flat collar bearing
24.

## The frictional torque produced due to friction for same shaft diameter, in conical bearing is____.

A. less than that for flat collar bearing
B. equal to that for flat collar bearing
C. more than that for flat collar bearing
D. may be more or less depending upon cone angle
Answer» C. more than that for flat collar bearing
25.

## Choose the wrong statement

A. the frictional torque transmitted by a shaft fitted with a large number of collars is the same as transmitted by a shaft with one collar
B. the frictional force for uniform pressure, in case of a flat pivot bearing, can be assumed to be acting at a distance of two-thirds of the radius of the shaft from the axis of shaft.
C. when horse power lost in friction is to be determined, uniform pressure is assumed for safe design of bearing
D. the frictional force for uniform pressure, in case of a flat collar pivot bearing, can be assumed to be acting at a distance of half of the sum of internal and external radii of the shaft
Answer» D. the frictional force for uniform pressure, in case of a flat collar pivot bearing, can be assumed to be acting at a distance of half of the sum of internal and external radii of the shaft
26.

A. 1
B. (2/3)
C. (4/3)
D. (3/4)
27.

## In case of pivot bearing the rate of wear is _____.

A. maximum at the center of the contact area
B. zero at the center of contact
C. uniform throughout the contact area
D. zero at the maximum radius of the contact area
Answer» B. zero at the center of contact
28.

## The number of collars are provided to carry a fixed axial force in a flat collar bearing _______.

A. to increase torque
B. to decrease torque
C. to decrease intensity of pressure
D. to decrease intensity of pressure
Answer» C. to decrease intensity of pressure
29.

## In flat pivot bearing the total moment of friction force______.

A. for uniform wear is greater than that for uniform pressure
B. for uniform wear is less than that for uniform pressure
C. for uniform wear is equal to that for uniform pressure
D. for uniform wear may be more or less and cannot be predicted
Answer» B. for uniform wear is less than that for uniform pressure
30.

## To be safe side in the design, the unform pressure and uniform wear is assumed respectively_____.

A. for power transmitted by friction and power lost due to friction
B. for power lost due to friction and power transmitted by friction
C. for torque transmitted by friction and friction torque overcome
D. none of the above
Answer» B. for power lost due to friction and power transmitted by friction
31.

## Choose the correct statement for safe design.

A. for power lost in friction uniform wear is assumed
B. for power lost in friction uniform pressure is assumed
C. for power transmitted due to friction uniform pressure is assumed
D. for power transmitted due to friction or lost in friction uniform wear is assuned
Answer» B. for power lost in friction uniform pressure is assumed
32.

## Choose the correct statement for safe design.

A. for power transmitted by friction uniform wear is assumed
B. for power transmitted by friction uniform pressure is assumed
C. for power lost in friction and power transmitted uniform wear is assumed
D. power lost in friction and power transmitted uniform pressure is assuned
Answer» A. for power transmitted by friction uniform wear is assumed
33.

## The purpose of providing multiple collars on a flat collar pivot bearing is to ____.

A. establish self sustaining bearing conditions
B. increase the frictional resistance
C. distribute the axial load because of limiting bearing pressure on bearing
D. increase the power absorbed by the bearing
Answer» C. distribute the axial load because of limiting bearing pressure on bearing
34.

A. w
B. w/n
C. w/(n-1)
D. none of these
35.

A. 11.25 n-m
B. 15 n-m
C. 18.50 n-m
D. 20.0 n-m
36.

A. 11.25 n-m
B. 15 n-m
C. 18.50 n-m
D. 20.0 n-m
37.

A. 650 watt
B. 880 watt
C. 659.7 watt
D. 680.20 watt
38.

A. 493.875 watt
B. 880 watt
C. 659.7 watt
D. 680.20 watt
39.

A. 40.5 n-m
B. 42 n-m
C. 45.0 n-m
D. 48.5 n-m
40.

A. 1.94 kw
B. 1.84 kw
C. 2 kw
D. 2.5 kw
41.

## A flat footstep bearing 10 cm radius supports a load of 3 kN. The shaft runs at 600/π r.p.m. and co-efficient of friction is 0.1.The friction torque and frictional power in watts with uniform pressure are respectively.

A. 10 n-m and 400 watts
B. 20 n-m and 400 watts
C. 30 n-m and 600 watts
D. not possible to find for insufficient data
Answer» B. 20 n-m and 400 watts
42.

## A flat footstep bearing 10 cm radius supports a load of 3 kN. The shaft runs at 600/π r.p.m. and co-efficient of friction is 0.1. The friction torque and frictional power in watts with uniform wear are respectively.

A. 30 n-m and 600 watt
B. 15 n-m and 300 watts
C. 15 n-m and 600 watts
D. not possible to find for insufficient data
Answer» B. 15 n-m and 300 watts
43.

## A flat foot step bearing 225 mm in diameter supports a load of 7500 N. If the co-efficient of friction is 0.09 and the shaft rotates at 60 rpm, calculate the power lost in frictional torque and frictional power in watts with uniform pressure is ___.

A. 50.62 n-m and 317.92 watt
B. 60.62 n-m and 320.92 watt
C. 57.68 n-m and 321.92 watt
D. 55.50 n-m and 410.12 watt
Answer» A. 50.62 n-m and 317.92 watt
44.

## Following are the details pertaining to thrust bearing 1) External and internal dia of contacting surfaces-320 mm and 200 mm resp. 2) Axial load-80 kN 3)Pr. Intensity-350 kN/m2 4) shaft speed-400 rpm 5)coefficient of friction-0.06 Calculate power lost in overcoming friction. the frictional torque and power lost in frictional

A. 600.35 nm and 26.60 kw
B. 630.30 nm and 28.40 kw
C. 635.08 nm and 26.60 kw
D. 650.52 nm and 27.35 kw
Answer» C. 635.08 nm and 26.60 kw
45.

## A conical pivot supports a load of 20 kN, and its semicone angle is 41.81 degree. The friction coefficient is 0.06 and shaft runs at 200 rpm. The torque required to overcome friction and power lost in friction is

A. 135.20 nm and 2.93 kw
B. 125.40 nm and 2.93 kw
C. 130.35 nm and 2.53 kw
D. 135.36 nm and 2.83 kw
Answer» D. 135.36 nm and 2.83 kw
46.

## The clutch is a device used______

A. to absorb frictional torque
B. to absorb frictional power
C. to transmit power from on shaft to another
D. all of the above
Answer» C. to transmit power from on shaft to another
47.

## Advantages of positive clutch is_____

A. they can be engaged at high speed
B. they cause for high speed application
C. shock and noise is there during engagement
D. due to no slip between contact surfaces no heat is generated
Answer» D. due to no slip between contact surfaces no heat is generated
48.

## Disadvantages of positive clutch is______

A. they can be engaged at high speed
B. they don’t provide positive engaged
C. shock and noise is there during engagement
D. due to no slip between contact surfaces no heat is generated
Answer» C. shock and noise is there during engagement
49.

## Torque transmitted by friction clutch_______

A. is more on the assumption of uniform pressure as compared to uniform wear
B. is less on the assumption of uniform pressure as compared to uniform wear
C. is same on the assumption of uniform pressure and uniform wear
D. is more or less on the assumption of uniform pressure as compared to uniform wear depending upon material
Answer» A. is more on the assumption of uniform pressure as compared to uniform wear
50.

A. n+1
B. n-1
C. n
D. n-2
51.

## Frictional torque transmission through plate clutch is equivalent to____

A. conical pivot bearing
B. flat pivot bearing
C. trapezoidal pivot bearing
D. flat roller bearing
52.

## In case of cone clutch, power transmission is same as that of________

A. flat pivot bearing
B. flat collar bearing
C. trapezoidal pivot bearing
D. conical pivot bearing
53.

## Multiple clutch is kind of_________

A. positive clutch
B. cone clutch
C. centrifugal clutch
D. disc clutch
54.

## Among which clutch heat dissipation is a serious problem?

A. multiple clutch
B. positive clutch
C. cone clutch
D. centrifugal clutch
55.

## In case of clutch , uniform pressure theory is applicable for

A. old clutch
B. new clutch
C. rusted clutch
D. clutch made of hard material
56.

A. truck
B. racing car
C. hack saw
D. mopeds
57.

## A friction clutch should be designed on the assumption of

A. uniform wear
B. uniform pressure
C. constant friction
D. any one
58.

## Considering the safe design, the friction clutch should be designed _______

A. assuming uniform pressure
B. assuming uniform wear
C. assuming any criteria, either uniform pressure or uniform wear
D. assuming uniform pressure for high torque and uniform wear for low torque
59.

A. µ sinα
B. µ tanα
C. µ/sinα
D. µ/tanα
60.

## Frictional torque transmission through multi plate clutch is equivalent to____.

A. conical pivot bearing
B. flat pivot bearing
C. trapezoidal pivot bearing
D. flat roller bearing
61.

## In case of multiplate clutch, power transmission is same as that of ______.

A. flat pivot bearing
B. flat pivot bearing
C. trapezoidal pivot bearing
D. conical pivot bearing
62.

## Single plate clutch is a kind of _________.

A. positive clutch
B. cone clutch
C. centrifugal clutch
D. disc clutch
63.

## Which of the following is an example of friction clutch?

A. disc clutch
B. cone clutch
C. centrifugal clutch
D. all of the above
Answer» D. all of the above
64.

## The frictional torque transmitted by a disc clutch is same as that of _____.

A. flat pivot bearing
B. flat collar bearing
C. conical pivot bearing
D. trapezoidal pivot bearing
65.

## The frictional torque transmitted by a cone clutch is same as that of ____.

A. flat pivot bearing
B. flat collar bearing
C. conical pivot bearing
D. trapezoidal pivot bearing
66.

## For safe design, a frictional clutch is designed assuming ____.

A. uniform pressure theory
B. uniform wear theory
C. any one of the two
D. none of the above
67.

A. 2n
B. n
C. 2(n-1)
D. n-1
68.

## Friction torque transmitted by a disc or plat clutch is same as that of ____.

A. flat pivot bearing
B. flat collar bearing
C. conical pivot bearing
D. truncated conical pivot bearing
69.

A. n
B. n+1
C. n-1
D. n/2
70.

A. 10 cm
B. 15 cm
C. 16.25 cm
D. 22.5 cm
71.

## Torque transmitted by single plate clutch with axial spring load = 1 kN, and inner and outer radii of 10 cm and 15 cm and µ = 0.5 with assumption of uniform wear is ____.

A. 250 n-m
B. 125 n-m
C. 62.5 n-m
D. not possible to find with given data
72.

A. 200 n
B. 300 n
C. 400 n
D. 1280 n
73.

## Determine the axial force required to engage a cone clutch transmitting 25 kW power at 750 rpm. Average friction diameter of the cone is 400 mm, semicone angle 10 degree and coefficient of friction 0.25.

A. 325.30 nm and 1100.25 n
B. 318.31 nm and 1105.47 n
C. 320.25 nm and 1008.20 n
D. 325.89 nm and 1120.30 n
Answer» B. 318.31 nm and 1105.47 n
74.

## Determine the axial force required to engage a cone clutch transmitting 25 kW power at 750 rpm. Average friction diameter of the cone is 400 mm, semicone angle 60 degree and coefficient of friction 0.25.

A. 325.30 nm and 1100.25 n
B. 318.31 nm and 1105.47 n
C. 320.25 nm and 1008.20 n
D. 325.89 nm and 1120.30 n
Answer» B. 318.31 nm and 1105.47 n
75.

## Can simple band brake be made of self-locking type?

A. yes
B. yes, but it will need many modifications
C. yes, but with few limitations
D. no
Answer» C. yes, but with few limitations
76.

## Material used for brake lining should not have ___.

A. high heat dissipation capacity
B. low heat resistance
C. high strength
D. high coefficient of friction
77.

## pivoted block brake is a kind of ____.

A. single block brake
B. shoe brake
C. differential expanding band brake
D. internal expanding shoe brake
78.

## Which type of brakes are used in electric crane?

A. internal expanding shoe brake
B. differential band brake
C. single block brake
D. double bloke brake
79.

A. a > b
B. a = b
C. a < b
D. a = b2
80.

## Brakes used in Railway engine are____.

A. band brake
B. internal expending brake
C. shoe brake
D. band and block brake
81.

## The brake commonly used in motor cars ____.

A. shoe brake
B. band brake
C. band and block brake
D. internal expanding brake
82.

## When will the distance travelled by 4-wheel be less after braking?

A. applied to rear wheel
B. when brakes applied to front wheel
C. when brakes applied to all 4-wheels
D. when brakes applied to rear wheel gradually
Answer» C. when brakes applied to all 4-wheels
83.

## Brakes are self energizing when____.

A. frictional torque assists the applied torque
B. frictional torque opposes the applied torque
C. frictional torque vanishes
D. none of the above
Answer» B. frictional torque opposes the applied torque
84.

## In a differential band brake, as shown in fig.1the length OA is greater than OB. In order to apply the brake, the force at C should____.

A. be zero
B. act in upward direction
C. act in downward direction
D. none of the above
Answer» C. act in downward direction
85.

## For the brake to be self locking, the force P at C as shown in fig.1 should____.

A. be zero
B. act in upward direction
C. act in downward direction
D. none of the above
86.

## When brakes are applied to all the four wheels of a moving car before it is brought to rest, will be____.

A. maximum
B. minimum
C. both (a) and (b)
D. none of the above
87.

## Which of the following brakes is commonly used in two wheelers?

A. disc brake
B. band brake
C. internal expanding shoe brake
88.

## Brakes commonly used in trains are _____brakes.

A. band
B. shoe
C. band and block
D. internal expanding brake
89.

## In a self locking brake, the force required to apply the brake is_____.

A. minimum
B. zero
C. maximum
D. none of the above
90.

## When the frictional force helps the applied force in applying the brake, the brake is____.

A. self locking
B. automatic
C. self-energizing
91.

## In an internal expanding shoe brake, more than 50% of the total braking torque is supplied by____.

B. trailing shoe
C. any of the above
D. none of these
92.

## Tractive resistance during the propulsion of a wheeled vehicle depends on____.

B. aerodynamic resistance b
D. all of the above
Answer» D. all of the above
93.

## A motor car uses____.

A. a band brake
B. a band and block brake
C. an external shoe brake
D. an internally expanding shoe brake
Answer» D. an internally expanding shoe brake
94.

## For a simple band brake to be effective____.

A. tight side is connected to free end of lever and effort is applied at end so as to move this end away from drum
B. same as (a) above but effort is so applied at end as to move this end towards the drum
C. slack side is connected to the free end of the lever and the effort is applied at end so as to move it away from drum
D. same as © but effort is applied at end so as to over this end towards the drum
Answer» D. same as © but effort is applied at end so as to over this end towards the drum
95.

## For ccw direction of drum rotation in fig.2 brake applied if ____.

A. a>b and p acts downwards
B. a<b and p acts downwards
C. a=b and p acts downwards
D. a>b and p acts upwards
Answer» A. a>b and p acts downwards
96.

## The band brake in fig.2 will be self-energizing when____.

A. drum rotates ccw and p acts upwards
B. drum rotates ccw and p acts downwards
C. drum rotates cw and p acts upwards
D. drum rotates ccw and p acts downwards
Answer» D. drum rotates ccw and p acts downwards
97.

## Self-locking is not possible in the case of____.

A. simple band brake
B. differential band brake
C. simple block brake
D. internal expanding brake
98.

A. 60
B. 120
C. 45
D. 90
99.

## In block brake, the normal reaction and frictional force act at the mid-point of the block. This is true only if the angle of contact is ____

A. less than 45 degree
B. less than 60 degree
C. greater than 45 degree
D. greater than 60 degree
Answer» A. less than 45 degree
100.

## In a block brake, when the fulcrum point is below the line of action of friction point, the ratio of effort required for clockwise and counter clockwise rotation is____.

A. equal to 1
B. greater than 1
C. less than 1
D. unpredictable