Theory Of Mechanics Set 1 MCQs

Q1 | The uniform wear conditions are used_____.

for maximum power to be transmitted

for safe design of clutches

for safe design bearing

for overcoming the frictional torque

Q2 | The uniform Pressure conditions are used_____.

for maximum power to be transmitted

for safe design of clutches

for safe design bearing

for overcoming the frictional torque

Q3 | For safe design of bearing, we assume____.

maximum power to be transmitted

safe design of clutches

safe design bearing

overcoming the frictional torque

Q4 | For safe design of clutches, we assume____.

uniform pressure conditions

uniform wear condition

neither uniform pressure nor uniform wear

all of the above

Q5 | According to uniform wear theory____. Where ,w=Angular velocity of shaft, r=radius of shaft, W=Axial lead on shaft

p.w=constant

p.r=constant

p.w=constant

p.t=constant

Q6 | In case of foot step bearing, the frictional force under the conditions of uniform pressure may be assumed to be acting at____.

r

(1/2).r

(3/2).r

(2/3)r

Q7 | In case of foot step bearing, the frictional force under the conditions of uniform wear may be assumed to be acting at____.

r

(1/2).r

(3/2).r

(2/3).r

Q8 | The ratio of friction torque for uniform pressure to uniform wear for the same dimensions and load is _______.

>1

1

<1

(1/2)

Q9 | Torque required to overcome the friction between shaft and bearing surface in case of multiple flat collar bearing is ___________.

independent on of collars

dependent on radius of collar

dependent of no of collars

none of above

Q10 | In case of flat pivot bearing,the rubbing velocity is _________.

maximum at the center of the contact area

zero at the center and maximum at the outer radius

uniform throughout the contact area

zero at the outer radius

Q11 | The rate of wearing in case of flat pivot bearing is ______.

inversely proportional to the pressure intensity

directly proportional to the rubbing velocity

directly proportionl to the pressure intensity

both (b) and (c )

Q12 | For calculating the friction power for bearing, the assumptions made in practice are_____.

the rate of wearing at the surface is uniform

the rubbing velocity is constant

the pressure intensity is uniform

(a) and (c ) only

Q13 | In case of flat pivot bearing the frictional torque transmitted for uniform pressure as compared to the frictional torque transmitted for uniform wear_____.

is more

is less

is constant

may be more or less

Q14 | The ratio of friction torque transmitted for uniform pressure to frictional torque transmitted for uniform wear in case of flat pivot, is equal to_______.

(1/3)

(2/3)

1

(4/3)

Q15 | 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____.

to reduce the frictional torque

to increase the frictional torque

to reduce the intensity of pressure

to increse the intensity of pressure

Q16 | Choose the correct statement regarding the safe design of a bearing.

when horse power lost in friction is to be determined, uniform rate of wear is assumed

when horse power transmitted is to be determined, uniform pressure is assumed

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

none of the above

Q17 | For uniform pressure the ratio of frictional torque for a flat collar bearing to the frictional torque for conical collar bearing is equal to____. Where ϴ=semi-angle of the cone

1.33

1

sinϴ

cosϴ

Q18 | For uniform wear, the ratio of frictional torque for a flat collar bearing to the frictional torque for conical collar bearing is equal to____. Where ϴ=semi-angle of the cone

1.33

1

sinϴ

cosϴ

Q19 | The ratio of frictional torque for a conical collar bearing to that for flat collar bearing is proportional to____. Where ϴ=semi-angle of the cone

sinϴ

cosϴ

tanϴ

1/sinϴ

Q20 | For flat and conical pivots, the ratio of friction torque with uniform wear to friction torque with uniform pressure is ____.

(2/3)

(3/2)

(4/3)

(3/4)

Q21 | The ratio of frictional torque produced for uniform wear to frictional torque produced for uniform pressure is ____.

(3/4)

(4/3)

(2/3)

1

Q22 | The frictional torque for the same diameter in a conical bearing is ____.

more

less

equal

may be more or less

Q23 | The frictional torque transmitted by a conical bearing is ____.

less than that of flat collar bearing

equal to that of flat collar bearing

more than that of flat collar bearing

none of the above

Q24 | The frictional torque produced due to friction for same shaft diameter, in conical bearing is____.

less than that for flat collar bearing

equal to that for flat collar bearing

more than that for flat collar bearing

may be more or less depending upon cone angle

Q25 | Choose the wrong statement

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

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.

when horse power lost in friction is to be determined, uniform pressure is assumed for safe design of bearing

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