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# Multiple choice question for engineering

## Set 1

1. The power from the engine to the rear axle of an automobile is transmitted by means of
a) worm and worm wheel
b) spur gears
c) bevel gears
d) hooke’s joint

Answer: d [Reason:] A Hooke’s joint is used to connect two shafts, which are intersecting at a small angle. In automobiles, the power is transmitted through this only.

2. A force acting in the opposite direction to the motion of the body is called force of friction.
a) True
b) False

Answer: a [Reason:] The force of friction always acts in a direction, opposite to that in which the body tends to move.

3. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as
a) static friction
b) dynamic friction
c) limiting friction
d) coefficient of friction

Answer: c [Reason:] The friction, experienced by a body, when at rest, is known as static friction. The friction, experienced by a body, when in motion, is known as dynamic friction. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as limiting friction.

4. The friction experienced by a body, when at rest, is known as static friction.
a) True
b) False

Answer: a [Reason:] The friction, experienced by a body, when at rest, is known as static friction. The friction, experienced by a body, when in motion, is known as dynamic friction. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as limiting friction.

5. The dynamic friction is the friction experienced by a body, when the body
a) is in motion
b) is at rest
c) just begins to slide over the surface of the other body
d) none of the mentioned

Answer: a [Reason:] The friction, experienced by a body, when at rest, is known as static friction. The friction, experienced by a body, when in motion, is known as dynamic friction. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as limiting friction.

6. 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 mentioned

Answer: d [Reason:] The laws of static friction are: a) The force of friction always acts in a direction, opposite to that in which the body tends to move. b) The magnitude of the force of friction is exactly equal to the force, which tends to move. c) The force of friction is independent of the area of contact, between the two surfaces. d) The force of friction depends upon the roughness of the surfaces.

7. Which of the following statements regarding laws governing the friction between dry surfaces are correct?
a) The friction force is dependent on the materials of the contact surfaces.
b) The friction force is directly proportional to the normal force.
c) The friction force is independent of the area of contact.
d) All of the mentioned

Answer: d [Reason:] The laws of friction between dry surfaces are: a) The force of friction always acts in a direction, opposite to that in which the body tends to move. b) The magnitude of the force of friction is exactly equal to the force, which tends to move. c) The force of friction is independent of the area of contact, between the two surfaces. d) The force of friction depends upon the roughness of the surfaces.

8. The angle of the inclined plane at which the body just begins to slide down the plane, is called helix angle.
a) True
b) False

Answer: b [Reason:] The angle of the inclined plane at which the body just begins to slide down the plane, is called angle of repose.

9. The angle which the normal reaction makes with the resultant reaction is called angle of friction.
a) True
b) False

Answer: a [Reason:] The angle of the inclined plane at which the body just begins to slide down the plane, is called angle of repose. The angle which the normal reaction makes with the resultant reaction is called angle of friction.

10. The angle of inclination of the plane, at which the body begins to move down the plane is called
a) angle of friction
b) angle of repose
c) angle of projection
d) none of the mentioned

Answer: b [Reason:] The angle of the inclined plane at which the body just begins to slide down the plane, is called angle of repose. The angle which the normal reaction makes with the resultant reaction is called angle of friction.

## Set 2

1. Which of the following screw thread is used for jacks, vices and clamps?

Answer: a [Reason:] The square threads are employed in screw jacks, presses and clamping devices.

2. Which of the following screw thread is used for transmitting force in one direction?

Answer: c [Reason:] A buttress thread, is used when large forces act along the screw axis in one direction only. This thread combines the higher efficiency of square thread and the ease of cutting and the adaptability to a split nut of acme thread.

3. Which of the following screw thread is adaptable to split type nut?

Answer: b [Reason:] An acme or trapezoidal thread, is a modification of square thread. The slight slope given to its sides lowers the efficiency slightly than square thread and it also introduce some bursting pressure on the nut, but increases its area in shear. It is used where a split nut is required and where provision is made to take up wear as in the lead screw of a lathe.

4. Which of the following screw thread is stronger than other threads?

Answer: c [Reason:] Buttress thread is stronger than other threads because of greater thickness at the base of the thread. The buttress thread has limited use for power transmission. It is employed as the thread for light jack screws and vices.

5. Which of the following screw thread is used for lead screw of lathe?

Answer: b [Reason:] The square threads are employed in screw jacks, presses and clamping devices. For lead screw of lathe, trapezoidal threads are used.

6. For self locking screw
a) φ > α
b) α > φ
c) μ < tanα
d) μ = cosecα

Answer: a [Reason:] If φ < α, then torque required to lower the load will be negative. In other words, the load will start moving downward without the application of any torque. Such a condition is known as over hauling of screws. If however, φ > α, the torque required to lower the load will be positive, indicating that an effort is applied to lower the load. Such a screw is known as self locking screw.

7. For over hauling screw
a) φ > α
b) α > φ
c) φ > α
d) none of the mentioned

Answer: b [Reason:] If φ > α, then torque required to lower the load will be negative. In other words, the load will start moving downward without the application of any torque. Such a condition is known as over hauling of screws. If however, φ > α, the torque required to lower the load will be positive, indicating that an effort is applied to lower the load. Such a screw is known as self locking screw.

8. A cup is provided in screw jack
a) to reduce the friction
b) to prevent rotation of load
c) to increase load capacity
d) to increase efficiency

Answer: b [Reason:] For the prevention of the rotation of load being lift, the load cup of a screw jack is made separate from the head of the spindle.

9. The maximum efficiency of square threaded power depends upon
a) lead angle of screw
b) friction angle
c) pitch of screw
d) nominal diameter of screw

Answer: b [Reason:] The efficiency of a square threaded screw depends upon the helix angle α and the friction angle φ.

10. The efficiency of square threaded power depends upon
a) mean diameter of screw
b) coefficient of friction
c) pitch of screw
d) all of the mentioned

## Set 3

1. In a simple gear train, if the number of idle gears is odd, then the motion of driven gear will
a) be same as that of driving gear
b) be opposite as that of driving gear
c) depend upon the number of teeth on the driving gear
d) none of the mentioned

Answer: a [Reason:] The speed ratio and the train value, in a simple train of gears, is independent of the size and number of intermediate gears. These intermediate gears are called idle gears, as they do not effect the speed ratio or train value of the system.

2. The train value of a gear train is
a) equal to velocity ratio of a gear train
b) reciprocal of velocity ratio of a gear train
c) always greater than unity
d) always less than unity

Answer: b [Reason:] Train value = Speed of the last driven or follower/Speed of the first driver.

3. When the axes of first and last gear are co-axial, then gear train is known as
a) simple gear train
b) compound gear train
c) reverted gear train
d) epicyclic gear train

Answer: c [Reason:] When the axes of the first gear (i.e. first driver) and the last gear (i.e. last driven or follower) are co-axial, then the gear train is known as reverted gear train. When there are more than one gear on a shaft, as shown in Fig. 13.2, it is called a compound train.

4. In a clock mechanism, the gear train used to connect minute hand to hour hand, is
a) epicyclic gear train
b) reverted gear train
c) compound gear train
d) simple gear train

Answer: b [Reason:] The reverted gear trains are used in automotive transmissions, lathe back gears, industrial speed reducers, and in clocks (where the minute and hour hand shafts are co-axial.

5. In a gear train, when the axes of the shafts, over which the gears are mounted, move relative to a fixed axis, is called
a) simple gear train
b) compound gear train
c) reverted gear train
d) epicyclic gear train

Answer: d [Reason:] In an epicyclic gear train, the axes of the shafts, over which the gears are mounted, may move relative to a fixed axis. When the axes of the first gear (i.e. first driver) and the last gear (i.e. last driven or follower) are co-axial, then the gear train is known as reverted gear train. When there are more than one gear on a shaft, as shown in Fig. 13.2, it is called a compound train of gear.

6. A differential gear in an automobile is a
a) simple gear train
b) epicyclic gear train
c) compound gear train
d) none of the mentioned

Answer: b [Reason:] The epicyclic gear trains are useful for transmitting high velocity ratios with gears of moderate size in a comparatively lesser space. The epicyclic gear trains are used in the back gear of lathe, differential gears of the automobiles, hoists, pulley blocks, wrist watches etc.

7. A differential gear in automobilies is used to
a) reduce speed
b) assist in changing speed
c) provide jerk-free movement of vehicle
d) help in turning

Answer: d [Reason:] For turning differential gears are used.

8. The gear train usually employed in clocks is a
a) reverted gear train
b) simple gear train
c) sun and planet gear
d) differential gear

Answer: a [Reason:] In reverted gear train and last gear train is on the same axis. Such an arrangement has application on speed reducers clocks and machine tools.

9. The working depth of an involute gear is equal to
b) dedendum
c) addendum + dedendum
d) 2 x addendum

Answer: d [Reason:] Working depth is twice of addendum and whole depth is sum of addendum and dedendum.

10. Tooth thickness on pitch line of involute gear in terms of module (m) is equal to
a) 1.157 m
b) 1.167 m
c) 2 m
d) 1.5708

Answer: d [Reason:] Tooth thickness = 1.5708 x module.

## Set 4

1. Radial distance between the pitch circle and the top of the tooth is known as
a) pitch
c) base circle
d) none of the mentioned

Answer: b [Reason:] The circle from which an involute curve is generated is known as base circle. Radial distance between the pitch circle and the top of the tooth is known as addendum.

2. The circle from which an involute curve is generated is known as
a) pitch
c) base circle
d) none of the mentioned

Answer: c [Reason:] The circle from which an involute curve is generated is known as base circle. Radial distance between the pitch circle and the top of the tooth is known as addendum.

3. Length of the arc of the pitch circle between the centres or other corresponding points of adjacent teeth is known as
a) pitch
b) circular pitch
c) base circle
d) none of the mentioned

Answer: b [Reason:] Length of the arc of the pitch circle between the centres or other corresponding points of adjacent teeth is known as circular pitch. The circle from which an involute curve is generated is known as base circle. Radial distance between the pitch circle and the top of the tooth is known as addendum.

4. The curve formed by the point on a circle as it rolls along a straight line is known as
a) cycloid
c) base circle
d) none of the mentioned

Answer: a [Reason:] Length of the arc of the pitch circle between the centres or other corresponding points of adjacent teeth is known as circular pitch. The circle from which an involute curve is generated is known as base circle. The curve formed by the point on a circle as it rolls along a straight line is known as cycloid.

5. That surface of the tooth which is between the pitch circle and the top of the tooth is known as
a) cycloid
c) face of tooth
d) none of the mentioned

Answer: c [Reason:] The circle from which an involute curve is generated is known as base circle. The curve formed by the point on a circle as it rolls along a straight line is known as cycloid. That surface of the tooth which is between the pitch circle and the top of the tooth is known as face of tooth.

6. The distance between similar, equally spaced tooth surfaces, in a given direction and along a given curve or line is known as
a) pitch
c) base circle
d) none of the mentioned

Answer: a [Reason:] The curve formed by the point on a circle as it rolls along a straight line is known as cycloid. That surface of the tooth which is between the pitch circle and the top of the tooth is known as face of tooth. The distance between similar, equally spaced tooth surfaces, in a given direction and along a given curve or line is known as pitch.

7. The angle between a tooth profile and a radial line at its pitch point is known as
a) pressure angle
b) dedendum angle
c) spiral angle
d) none of the mentioned

Answer: a [Reason:] The angle subtended at the centre of a base circle from the origin of an involute to the point of tangency of the generatrix from any point on the same involute is known as roll angle. The angle between a tooth profile and a radial line at its pitch point is known as pressure angle.

8. The angle subtended at the centre of a base circle from the origin of an involute to the point of tangency of the generatrix from any point on the same involute is known as
a) pressure angle
b) dedendum angle
c) roll angle
d) none of the mentioned

Answer: c [Reason:] The angle subtended at the centre of a base circle from the origin of an involute to the point of tangency of the generatrix from any point on the same involute is known as roll angle. The angle between a tooth profile and a radial line at its pitch point is known as pressure angle.

9. Surface of the gear between the fillets of adjacent teeth is known as
a) cycloid
c) bottom land
d) none of the mentioned

Answer: c [Reason:] Surface of the gear between the fillets of adjacent teeth is known as bottom land.

10. The angle, at the base cylinder of an involute gear, that the tooth makes with the gear axis is known as
a) pressure angle
b) base helix angle
c) roll angle
d) none of the mentioned

Answer: b [Reason:] The angle subtended at the centre of a base circle from the origin of an involute to the point of tangency of the generatrix from any point on the same involute is known as roll angle. The angle between a tooth profile and a radial line at its pitch point is known as pressure angle. The angle, at the base cylinder of an involute gear, that the tooth makes with the gear axis is known as base helix angle.

## Set 5

1. The approximate straight line mechanism is a
a) 4 bar linkage
b) 6 bar linkage
c) 8 bar linkage
d) 3 bar linkage

Answer: a [Reason:] The straight line mechanism has 4 bar linkage.

2. Open pairs are those which have
a) point or line contact between the two elements when in motion
b) surface contact between the two elements when in motion
c) elements of pairs not held together mechanically
d) two elements that permit relative motion

Answer: c [Reason:] Two elemets which are not held together form open pairs. Two elements held together mechanically form a closed pair.

3. Peaucellier mechanism has

Answer: a [Reason:] Peaucellier mechanism has 8 links. Hart mechanism has 6 links.

4. Hart mechanism has

Answer: b [Reason:] Hart mechanism has 6 links. Peaucellier mechanism has 8 links.

5. A chain comprises of 5 links having 5 joints. Is it kinematic chain?
a) Yes
b) No
c) It is a marginal case
d) None of the mentioned

Answer: b [Reason:] Kinematic chain is one which satisfies L = 2/3 (J + 2), which is not satisfied in this case.

6. In the following equation [ L = 2/3(J + 2)] to determine whether or not the given chain in kinematic, higher pair is treated equivalent to
a) two lower pairs and an additional links
b) two higher pairs and two additional links
c) one lower pairs and two additional links
d) none of the mentioned

Answer: a [Reason:] In the above equation, each higher pair is taken equivalent to two lower pairs and an additional link. If one of the links of the constrained chain is fixed, it results into mechanism.

7. The main disadvantage of the sliding pair is that it is
a) bulky
b) difficult to manufacture
c) wears rapidly
d) both a and c

Answer: d [Reason:] The sliding pair wears rapidly due to friction and is bulky also.

8. For a kinematic chain to be considered as mechanism
a) two links should be fixed
b) one link should be fixed
c) none of the links should be fixed
d) there is no such criterion

Answer: b [Reason:] If one of the links of the constrained chain is fixed, it results into mechanism.

9. An eccentric sheave pivoted at one point rotates and transmits oscillatory motion to a link whose one end is pivoted and other end is connected to it. This mechanism has

Answer: c [Reason:] Eccentric sheave is equivalent to 2 links, 1 link is due to oscillatory link, and one is fixed link.

10. Whitworth quick return mechanism is obtained by inversion of
a) slider crank mechanism
b) kinematic chain
c) five link mechanism
d) roller cam mechanism