Category: Machine Kinematics Objective Questions

Machine Kinematics Multiple Choice Questions on “Friction of a V-thread”.

1. Which of the following screw thread is used for jacks, vices and clamps?
a) square thread
b) trapezoidal threads
c) buttress threads
d) acme threads
Answer: a
Clarification: 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?
a) square thread
b) trapezoidal threads
c) buttress threads
d) v threads
Answer: c
Clarification: 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?
a) square thread
b) trapezoidal threads
c) buttress threads
d) v threads
Answer: b
Clarification: 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?
a) square thread
b) trapezoidal threads
c) buttress threads
d) V threads
Answer: c
Clarification: 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?
a) square thread
b) trapezoidal threads
c) buttress threads
d) V threads
Answer: b
Clarification: 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
Clarification: 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
Clarification: 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
Clarification: 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
Clarification: 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
Answer: d
Clarification: None.

Machine Kinematics Multiple Choice Questions on “Types of Gear Trains”.

1. A fixed gear having 200 teeth is in mesh with another gear having 50 teeth. The two gears are connected by an arm. The number of turns made by the smaller gear for one revolution of arm about the centre of bigger gear is
a) 2
b) 4
c) 3
d) none of the mentioned
Answer: b
Clarification: N₁ = 200
N₂ = 50
Number of turns = N₁/N₂
= 200/50 = 4.

2. Number of teeth on a wheel per unit of its pitch diameter is called
a) module
b) diametral pitch
c) circular pitch
d) none of the mentioned
Answer: b
Clarification: None.

3. The type of gears used to connect two non parallel and non intersecting shafts is
a) Spur gear
b) Helical gear
c) Bevel gear
d) Spiral gear
Answer: d
Clarification: Spiral gear is used connect two non parallel and non intersecting shafts. Spur gear is used to connect two parallel and coplanar shafts.

4. To connect two parallel and coplanar shafts the following type of gearing is used
a) Spur gear
b) Bevel gear
c) Spiral gear
d) None of the mentioned
Answer: a
Clarification: Spiral gear is used connect two non parallel and non intersecting shafts. Spur gear is used to connect two parallel and coplanar shafts.

5. In which of the following type of gear train the first gear and the last gear are co-axial.
a) Simple gear train
b) Compound gear train
c) Reverted gear train
d) None of the mentioned
Answer: c
Clarification: 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.

6. Which gear train is used for higher velocity ratios in a small space?
a) Simple gear train
b) Compound gear train
c) Reverted gear train
d) Epicyclic gear train
Answer: d
Clarification: 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. Which type of gear train is used in clock mechanism to join hour hand and minute hand?
a) Simple gear train
b) Compound gear train
c) Reverted gear train
d) Epicyclic gear train
Answer: d
Clarification: The epicyclic gear trains are used in the back gear of lathe, differential gears of the automobiles, hoists, pulley blocks, wrist watches etc.

8. The gear used to convert rotary motion into translating motion is
a) Worm and wheel
b) Crown gear
c) Rack and pinion
d) Spiral Bevel gear
Answer: c
Clarification: Rack and pinion gears are used to convert rotation into linear motion. The flat, toothed part is the rack and the gear is the pinion. A piston coaxial to the rack provides hydraulic assistance force, and an open centered rotary valve controls the assist level.

9. The circular pitch of a gear is given by
a) Πd/t
b) Πd/2t
c) 2Πd/t
d) Πd/3t
Answer: a
Clarification: The distance measured along the pitch circle from a point on one tooth to the corresponding point on an adjacent tooth is called circular pitch.
P_c = Πd/t
Where d=diameter of pitch circle
t=number of teeth.

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

Machine Kinematics Multiple Choice Questions on “Contact Ratio”.

1. The tooth profile most commonly used in gear drives for power transmission is
a) A cycloid
b) An involute
c) An ellipse
d) A parabola
Answer: b
Clarification: It is due to easy manufacturing.

2. There are six gears A, B, C, D, E, F in a compound train. The numbers of teeth in the gears are 20, 60, 30, 80, 25 and 75 respectively. The ratio of the angular speeds of the driven (F) to the driver (A) of the drive is
a) 1/24
b) 1/8
c) 4/15
d) 12
Answer: a
Clarification: The ratio of angular speeds of F to A = T_A.T_C.T_E/T_B.T_D.T_F
= 20 x 30 x 25/60 x 80 x 75
= 1/24.

3. A fixed gear having 100 teeth meshes with another gear having 25 teeth, the centre lines of both the gears being joined by an arm so as to form an epicyclic gear train. The number of rotations made by the smaller gear for one rotation of the arm is
a) 3
b) 4
c) 5
d) 6
Answer: c
Clarification: Revolution of 25 teeth gear = 1 + T₁₀₀/T₂₅
= 1 + 100/25 =5.

4. Speed reduction in a gear box is achieved using a worm and worm wheel. The worm wheel has 30 teeth and a pitch diameter of 210 mm. If the pressure angle of the worm is 20^o, what is the axial pitch of the worm?
a) 7 mm
b) 22 mm
c) 14 mm
d) 63 mm
Answer: b
Clarification: m = 210/30 = 7
P = πm = 22/7 x 7
= 22 mm
Axial pitch = circular pitch of the worm wheel = πm.

5. A speed reducer unit consists of a double-threaded worm of pitch = 11 mm and a worm wheel of pitch diameter = 84 mm. The ratio of the output torque to the input to rque is
a) 7·6
b) 12
c) 24
d) 42
Answer: a
Clarification: Output torque/Input torque = pitch diameter of worm wheel/ pitch of worm
= 84/11
= 7.6.

6. A pair of gears forms a rolling pair.
a) True
b) False
Answer: b
Clarification: In rolling pair one link rolls over another fixed link.

7. Spiral bevel gears designed to be used with an offset in their shafts are called ‘hypoid gears’
a) True
b) False
Answer: a
Clarification: The pitch surfaces of such gears are hyperboloids of revolution.

8. Gears with involute tooth profile transmit constant velocity ratios between shafts connected by them.
a) True
b) False
Answer: a
Clarification: For involute gears, the common normal at the point of contact between pairs of teeth always passes through the pictch point.

9. In the case of spur gears, the mating teeth execute pure rolling motion with respect to each other from the commencement of engagement to its termination.
a) True
b) False
Answer: a
Clarification: The involute profiles of the mating teeth are conjugate profiles which obey the law of gearing.

10. A pair of helical gears has fewer teeth in contact as compared to an equivalent pair of spur gears.
a) True
b) False
Answer: b
Clarification: In spur gears, the contact between meshing teeth occurs along the entire face width of the tooth, resulting in a sudden application of the load which, in turn, results in impact conditions and generates noise.

Machine Kinematics Multiple Choice Questions on “Linear Acceleration”.

1. The acceleration of a particle at any instant has two components, radial component and tangential component. These two components will be
a) parallel to each other
b) perpendicular to each other
c) inclined at 45⁰
d) opposite to each other
Answer: b
Clarification: Both the components will be perpendicular to each other.

2. The centre of gravity of a coupler link in a four bar mechanism will experience
a) no acceleration
b) only linear acceleration
c) only angular acceleration
d) both linear and angular acceleration
Answer: d
Clarification: None

3. When a point moves along a straight line, its acceleration will have
a) radial component only
b) tangential component only
c) coriolis component only
d) radial and tangential components both
Answer: b
Clarification: The tangential component, is parallel to the velocity of the particle at the given instant.
The centripetal or radial component, is perpendicular to the velocity of the particle at the given instant.

4. When a point at the end of a link moves with constant angular velocity, its acceleration will have
a) radial component only
b) tangential component only
c) coriolis component only
d) radial and tangential components both
Answer: a
Clarification: The centripetal or radial component, is perpendicular to the velocity of the particle at the given instant.
The tangential component, is parallel to the velocity of the particle at the given instant.

5. In a shaper mechanism, the coriolis component of acceleration does not exists.
a) True
b) False
Answer: b
Clarification: In a shaper mechanism, the coriolis component of acceleration exists.

6. The tangential component of acceleration of the slider with respect to the coincident point on the link is called coriolis component of acceleration.
a) True
b) False
Answer: a
Clarification: When a point on one link is sliding along another rotating link, such as in quick return motion mechanism, then the coriolis component of the acceleration must be calculated.

7. The coriolis component of acceleration acts
a) along the sliding surface
b) perpendicular to the sliding surface
c) at 45⁰ to the sliding surface
d) parallel to the sliding surface
Answer: b
Clarification: None

8. The coriolis component of acceleration is taken into account for
a) slider crank mechanism
b) four bar chain mechanism
c) quick return motion mechanism
d) all of the mentioned
Answer: c
Clarification: When a point on one link is sliding along another rotating link, such as in quick return motion mechanism, then the coriolis component of the acceleration must be calculated.

9. The coriolis component of acceleration depends upon
a) velocity of slider
b) angular velocity of the link
c) all of the mentioned
d) none of the mentioned
Answer: c
Clarification: None

10. A body in motion will be subjected to coriolis acceleration when that body is
a) in plane rotation with variable velocity
b) in plane translation with variable velocity
c) in plane motion which is a resultant of plane translation and rotation
d) restrained to rotate while sliding over another body
Answer: d
Clarification: When a point on one link is sliding along another rotating link, such as in quick return motion mechanism, then the coriolis component of the acceleration must be calculated.

11. A slider moves at a velocity v on a link revolving at ωrad/s. The coriolis component of acceleration is
a) ωv
b) 2ωv
c) ω²v
d) 2ωv²
Answer: b
Clarification: None

12. The coriolis component of acceleration leads the sliding velocity by
a) 45⁰
b) 90⁰
c) 135⁰
d) 180⁰
Answer: b
Clarification: The direction of coriolis component of acceleration is obtained by rotating v, at 90°, about its origin in the same direction as that of ω.

13. The sense of coriolis component 2ωv is same as that of the relative velocity vector v rotated at
a) 45⁰ in the direction of rotation of the link containing the path
b) 45⁰ in the direction opposite to the rotation of the link containing the path
c) 90⁰ in the direction of rotation of the link containing the path
d) 180⁰ in the direction opposite to the rotation of the link containing the path
Answer: c
Clarification: The direction of coriolis component of acceleration is obtained by rotating v, at 90°, about its origin in the same direction as that of ω.

Machine Kinematics Multiple Choice Questions on “Simple Mechanisms – 1”.

1. In a reciprocating steam engine, which of the following forms a kinematic link ?
a) cylinder and piston
b) piston rod and connecting rod
c) crank shaft and flywheel
d) flywheel and engine frame
Answer: c
Clarification: in a reciprocating steam engine, piston, piston rod and crosshead constitute one link ; connecting rod with big and small end bearings constitute a second link ; crank, crank shaft and flywheel a third link and the cylinder, engine frame and main bearings a fourth link.

2. The motion of a piston in the cylinder of a steam engine is an example of
a) completely constrained motion
b) incompletely constrained motion
c) successfully constrained motion
d) none of the mentioned
Answer: a
Clarification: The piston and cylinder in a steam engine form a pair and the motion of the piston is limited to a definite direction (i.e. it will only reciprocate) relative to the cylinder irrespective of the direction of motion of the crank.

3. The motion transmitted between the teeth of gears in mesh is
a) sliding
b) rolling
c) may be rolling or sliding depending upon the shape of teeth
d) partly sliding and partly rolling
Answer: d
Clarification: When the two elements of a pair have a line or point contact when relative motion takes place and the motion between the two elements is partly turning and partly sliding, and in mesh the gears have a point contact.

4. The cam and follower without a spring forms a
a) lower pair
b) higher pair
c) self closed pair
d) force closed pair
Answer: c
Clarification: When the two elements of a pair are connected together mechanically in such a way that only required kind of relative motion occurs, it is then known as self closed pair. The lower pairs are self closed pair and the motion of cam and follower is relative to each other.

5. A ball and a socket joint forms a
a) turning pair
b) rolling pair
c) sliding pair
d) spherical pair
Answer: d
Clarification: When the two elements of a pair are connected in such a way that one element (with spherical shape) turns or swivels about the other fixed element, the pair formed is called a spherical pair, and ball and socket joint are such pairs.

6. The lead screw of a lathe with nut forms a
a) sliding pair
b) rolling pair
c) screw pair
d) turning pair
Answer: c
Clarification: When the two elements of a pair are connected in such a way that one element can turn about the other by screw threads, the pair is known as screw pair. The lead screw of a lathe with nut, and bolt with a nut are examples of a screw pair.

7. When the elements of the pair are kept in contact by the action of external forces, the pair is said to be a
a) lower pair
b) higher pair
c) self closed pair
d) force closed pair
Answer: d
Clarification: When the two elements of a pair are not connected mechanically but are kept in contact by the action of external forces, the pair is said to be a force-closed pair. The cam and follower is an example of force closed pair, as it is kept in contact by the forces exerted by spring and gravity.

8. Which of the following is a turning pair ?
a) Piston and cylinder of a reciprocating steam engine
b) Shaft with collars at both ends fitted in a circular hole
c) Lead screw of a lathe with nut
d) Ball and socket joint
Answer: b
Clarification: When the two elements of a pair are connected in such a way that one can only turn or revolve about a fixed axis of another link, the pair is known as turning pair. A shaft with collars at both ends fitted into a circular hole, the crankshaft in a journal bearing in an engine, lathe spindle supported in head stock, cycle wheels turning over their axles etc. are the examples of a turning pair.

9. A combination of kinematic pairs, joined in such a way that the relative motion between the links is completely constrained, is called a
a) structure
b) mechanism
c) kinematic chain
d) inversion
Answer: c
Clarification: When the kinematic pairs are coupled in such a way that the last link is joined to the first link to transmit definite motion (i.e. completely or successfully constrained motion), it is called a kinematic chain. In other words, a kinematic chain may be defined as a combination of kinematic pairs, joined in such a way that each link forms a part of two pairs and the relative motion between the links or elements is completely or successfully constrained.

10. The relation between the number of pairs ( p ) forming a kinematic chain and the number of links (l) is
a) l = 2p – 2
b) l = 2p – 3
c) l = 2p – 4
d) l = 2p – 5
Answer: c
Clarification: If each link is assumed to form two pairs with two adjacent links, then the relation between the number of pairs ( p ) forming a kinematic chain and the number of links ( l ) may be expressed in the form of an equation :
l = 2 p – 4

Machine Kinematics Multiple Choice Questions on “Single Slider Crank Chain and its Inversions – 1”.

1. The quick return mechanism which is an inversion of 4-bar linkage is
a) Drag link mechanism
b) Whitworth quick return mechanism
c) Crank and slotted lever mechanism
d) None of the mentioned
Answer: a
Clarification: Drag link mechanism is an inversion of 4-bar linkage, which is a crank mechanism with different crank lengths. It is made up of revolute pairs only.

2. Match list I with list II
List I List II
A. Pantograph 1. Scotch yoke mechanism
B. Single slider crank 2. Double lever mechanism
C. Double slider crank chain 3. Tchebicheff’s mechanism
D. Straight line motion mechanism 4. Double crank
5. Hand pump
a) A-4,B-3,C-5,D-1
b) A-2,B-5,C-1,D-3
c) A-2,B-1,C-5,D-3
d) A-4,B-5,C-2,D-1
Answer: b
Clarification: Pantograph is double lever mechanism. handpump is an inversion of single slider crank chain. Scotch yoke mechanism is an inversion of double slider crank chain.Tchebiceff’s mechanism is an approximate straight line motion mechanism.

3. Match list I with list II
List I List II
A. Scott-Russel 1. Intemittent mechanism motion
B. Geneva 2. Quick return mechanism motion
C. Offset slider crank 3. Simple motion harmonic mechanism
D. Scotch Yoke 4. Straight line mechanism motion

a) A-2,B-3,C-1,D-4
b) A-3,B-2,C-4,D-1
c) A-4,B-1,C-2,D-3
d) A-4,B-3,C-1,D-2
Answer: c
Clarification: Scott-Russel – Straight line mechanism motion
Geneva – Intemittent mechanism motion
Offset slider crank – Quick return mechanism motion
Scotch Yoke – Simple motion harmonic mechanism.

4. When a cylinder is located in a Vee-block, the number of degrees of freedom which are arrested is
a) 2
b) 4
c) 7
d) 8
Answer: b
Clarification: Before placement on Vee-block, cylinder has 6 degrees of freedom. After placement on Vee-block, the cylinder has only 2 degrees of freedom. Hence, the degrees of freedom which are arrested is 6 – 2 = 4.

5. Match list I with list II

Type of joint Motion constrained
A. Revolute 1. Three
B. Cylindrical 2. Five
C. Spherical 3. Four
4. Two
5. Zero
a) A-1,B-3,C-2
b) A-5,B-4,C-3
c) A-2,B-3,C-1
d) A-4,B-5,C-3
Answer: c
Clarification: For revolute pair, degree of freedom = 1 and constrained
DOF = 6 – 1 = 5
For cylindrical pair, dof =2 and constrained dof = 6 – 2 = 4
For spherical pair, dof = 3 and constrained dof = 6 – 3 = 3.

6. The number of binary links, number of binary joints and number of ternary joints in Peaucelliar mechanism is
a) 6,6,0
b) 8,2,4
c) 8,4,2
d) 8,8,0
Answer: b
Clarification: The Peaucelliar mechanism has 8 binary links, 2 binary joints nad 4 ternary joints.

7. The number of degree of freedom of a planer linkage with 8 links and 9 simple revolute joints is
a) 1
b) 2
c) 3
d) 4
Answer: c
Clarification: L = 8 = number of links
P = 9 = number of simple revolute joints

F = 3(L – 1) – 2P
= 3(8 – 1) – 2 x 9
= 21 – 18
= 3.