Category: Machine Kinematics Objective Questions

Machine Kinematics Multiple Choice Questions on ” Mechanisms with Lower Pairs”.

1. A pantograph consists of
a) 4 links
b) 6 links
c) 8 links
d) 10 links
Answer: a
Clarification: In a pantograph, all the pairs are turning pairs. It has 4 links.

2. Which of these mechanisms gives an approximately straight line?
a) hart
b) watt
c) peaucellier
d) tchebicheff
Answer: b
Clarification: Watt’s mechanism is a crossed four bar chain mechanism and was used by Watt for his early steam engines to guide the piston rod in a cylinder to have an approximate straight line motion.

3. Which of these mechanism has six links?
a) tchebicheff
b) hart
c) peaucellier
d) watt
Answer: b
Clarification: Hart’s mechanism requires only six links as compared with the eight links required by the Peaucellier mechanism.

4. Which of these mechanisms use two identical mechanisms?
a) hart
b) watt
c) peaucellier
d) none of the mentioned
Answer: d
Clarification: None.

5. The Davis steering gear is not used because
a) it has turning pairs
b) it is costly
c) it has sliding pair
d) it does not fulfil the condition of correct gearing
Answer: b
Clarification: Though the gear is theoretically correct, but due to the presence of more sliding members, the wear will be increased which produces slackness between the sliding surfaces, thus eliminating the original accuracy. Hence Davis steering gear is not in common use.

6. The Davis steering gear fulfils the condition of correct steering at
a) two positions
b) three positions
c) all positions
d) one positions
Answer: c
Clarification: It can be used in all positions.
Ackermann steering gear fulfils the condition of correct steering at only three positions.

7. The Ackermann steering gear fulfils the condition of correct steering at
a) no position
b) one position
c) three positions
d) all positions
Answer: c
Clarification: Ackermann steering gear fulfils the condition of correct steering at only three positions.

8. A Hooke’s joint is used to join two shafts which are
a) aligned
b) intersecting
c) parallel
d) none of the mentioned
Answer: b
Clarification: Hooke’s joint is used to connect two shafts, which are intersecting at a small angle.

9. The maximum velocity of the driven shaft of a Hooke’s joint is
a) ω₁ cosα
b) ω₁/cosα
c) ω₁ sinα
d) ω₁/sinα
Answer: b
Clarification: Maximum speed of the driven shaft,
ω_1(max) = ωcosα/ 1 – sin²α = ωcosα/cos²α = ω/cosα.

10. The maximum velocity of the driven shaft of a Hooke’s joint is at ϴ equal to
a) 0⁰ and 180⁰
b) 90⁰ and 270⁰
c) 90⁰ and 180⁰
d) 180⁰ and 270⁰
Answer: a
Clarification: Maximum velocity is determined at 0⁰ ,180⁰ and 360⁰.

Machine Kinematics Multiple Choice Questions on “Friction in Journal Bearing- Friction Circle”.

1. The minimum force required to slide a body of weight W on a rough horizontal plane is
a) W sinϴ
b) W cosϴ
c) W tanϴ
d) W cosecϴ
Answer: a
Clarification: The minimum force required to slide a body of weight W on a rough horizontal plane is W sinϴ. A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is α. The effort applied parallel to the plane is given by P = W (sinα + μ cosα).

2. A body will begin to move down an inclined plane, if the angle of inclination of the plane is ____________ the angle of friction.
a) equal to
b) less than
c) greater than
d) none of the mentioned
Answer: c
Clarification: None.

3. A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is α. The effort applied parallel to the plane is given by
a) P = W tanα
b) P = W tan (α + ɸ)
c) P = W (sinα + μ cosα)
d) P = W (cosα + μ sinα)
Answer: c
Clarification: The minimum force required to slide a body of weight W on a rough horizontal plane is W sinϴ. A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is α. The effort applied parallel to the plane is given by P = W (sinα + μ cosα).

4. The coefficient of friction is the ratio of the limiting friction to the normal reaction between the two bodies.
a) True
b) False
Answer: a
Clarification: The coefficient of friction is defined as the ratio of the limiting friction(F) to the normal reaction(R_N) between the two bodies. Mathematically,
μ = F/R_N.

5. In a screw jack, the effort required to lift the load W is given by
a) P = W tan (α – ɸ)
b) P = W tan (α + ɸ)
c) P = W tan (ɸ – α)
d) P = W cos (α + ɸ)
Answer: b
Clarification: The effort required at the circumference of the screw to lift the load W is given by
P = W tan (α + ɸ)
The effort required at the circumference of the screw to lower the load W is given by
P = W tan (ɸ – α).

6. In a screw jack, the effort required to lower the load W is given by
a) P = W tan (α – ɸ)
b) P = W tan (α + ɸ)
c) P = W tan (ɸ – α)
d) P = W cos (α + ɸ)
Answer: c
Clarification: The effort required at the circumference of the screw to lower the load W is given by
P = W tan (ɸ – α)
The effort required at the circumference of the screw to lift the load W is given by
P = W tan (α + ɸ).

7. The frictional torque for square thread at the mean radius r while raising load W is given by
a) T = W.rtan(α – ɸ)
b) T = W.rtan(α + ɸ)
c) T = W.rtanα
d) T = W.rtanɸ
Answer: b
Clarification: None.

8. Efficiency of a screw jack is given by
a) tan(α + ɸ)/tanα
b) tanα/ tan(α + ɸ)
c) tan(α – ɸ)/tanα
d) tanα/tan(α – ɸ)
Answer: b
Clarification: None.

9. The load cup of a screw jack is made separate from the head of the spindle to
a) enhance the load carrying capacity of the jack
b) reduce the effort needed for lifting the working load
c) reduce the value of frictional torque required to be countered for lifting the load
d) prevent the rotation of load being lifted
Answer: d
Clarification: In screw jack, the load to be raised or lowered, is placed on the head of the square threaded rod which is rotated by the application of an effort at the end of the lever for lifting or lowering the load.

10. The efficiency of the a screw jack is maximum, when
a) α = 45⁰ + ɸ/2
b) α = 45⁰ – ɸ/2
c) α = 90⁰ + ɸ
d) α = 90⁰ – ɸ
Answer: b
Clarification: None.

Machine Kinematics Questions & Answers for Exams on “The Differential & Torques in Epicyclic Gear Trains”.

1. To split the engine torque in two ways, which of the following device is used?
a) Clutch
b) Brake
c) Final drive
d) Differential
Answer: d
Clarification: The differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed and hence considered as an immensely important device in the modern vehicles.

2. Two wheelers are also equipped with a differential.
a) True
b) False
Answer: b
Clarification: The differential is found on all modern cars and trucks, and also in many all-wheel-drive vehicles. Two wheelers do not have a differential.

3. Which of the following device allows the wheels of a car to rotate at two different speeds?
a) Clutch
b) Brake
c) Final drive
d) Differential
Answer: d
Clarification: The differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed. The differential plays an integral role in how a car makes turns.

4. Which of the following is true regarding a differential?
a) The outer wheel rotates at a higher speed than the inner wheel
b) The outer wheel rotates at a lower speed than the inner wheel
c) Both the wheels rotate at the same speed
d) Front wheels rotate at a lower speed than rear wheel
Answer: a
Clarification: Since the outer wheels of a car has to travel a greater distance, the outer wheel must rotate at a higher speed in order to prevent slipping.

5. The ratio of speeds between gears is dependent upon the _________
a) Ratio of teeth between the two adjoining gears
b) Ratio of teeth between the two alternate gears
c) Ratio of acceleration
d) Ratio of velocity
Answer: a
Clarification: The ratio of speeds between gears is dependent upon the ratio of teeth between the two adjoining gears such that w₁ x N₁ = w₂ x N₂ where w₁ is the teeth of gear one and N₁ is the speed.

6. On a straight road motion, what is the purpose served by differential?
a) Equal torque to all the wheels
b) More torque to front wheels
c) More torque to rear wheels
d) More torque to opposite wheels
Answer: a
Clarification: When the car is traveling straight, both wheels travel at the same speed. This is done by providing equal torque to all the wheels.

7. Input torque acts on which of the following member?
a) Driven member
b) Driving member
c) Fixed member
d) Reciprocating member
Answer: b
Clarification: If the rotating parts of an epicyclic gear trains does not undergo any acceleration then it is kept in equilibrium by an externally applied torques. The input torque is one of them and acts on the driving member.

8. Resisting torque acts on which of the following member?
a) Driven member
b) Driving member
c) Fixed member
d) Reciprocating member
Answer: a
Clarification: If the rotating parts of an epicyclic gear trains does not undergo any acceleration then it is kept in equilibrium by an externally applied torques. The input torque is one of them and acts on the driven member.

9. Braking torque acts on which of the following member?
a) Driven member
b) Driving member
c) Fixed member
d) Reciprocating member
Answer: c
Clarification: If the rotating parts of an epicyclic gear trains does not undergo any acceleration then it is kept in equilibrium by an externally applied torques. The input torque is one of them and acts on the fixed member.

10. If the input power is increased to two times, what will be the effect of it on the fixed member power?
a) Has a 0 value
b) Increases by two times
c) Increases by 4 times
d) Decreases by two times
Answer: a
Clarification: Since the fixed member does not rotate, the power transmitted by it is 0. As a result of this it remains unaffected by change in input power.

11. If the ratio of angular velocities of the driven and driving torque is one, find the Braking torque
a) 0
b) 2
c) 4
d) 8
Answer: a
Clarification: We know the relation
T₂ = -T₁ω₁/ω₂
since the velocity ratio is 1
we have T₂ + T₁ = 0
now
T₃ = T₂ + T₁
Therefore, T₃ = 0.

12. The angular speed of the driven member is twice the driving member, if the input torque is 100 N-m,
Find the load torque magnitude in N-m.
a) 50
b) 100
c) 200
d) 25
Answer: a
Clarification: We know the relation
T₂ = -T₁ω₁/ω₂
since the velocity ratio is ¹⁄₂
we have T₂ = 50 N-m.

13. Fixing torque’s value is independent of the load torque.
a) True
b) False
Answer: b
Clarification: Fixing torque or the braking torque or the Holding torque generally represented by T₃ has a value
T₃ = -(T₂ + T₁)
therefore its value is dependent on the load torque.

14. Load torque is directly proportional to the input angular velocity.
a) True
b) False
Answer: a
Clarification: We know that Load torque is given by
T₂ = -T₁ω₁/ω₂ where ω₁ is the input angular velocity. Hence the given statement is correct.

To practice all exam questions on Machine Kinematics,

Machine Kinematics Multiple Choice Questions on “Interference”.

1. Which of the following is a disadvantage of involute gears?
a) Occurrence of interference
b) Non occurrence of interference
c) Pressure angle remains constant
d) Face and flank are generated by single curve
Answer: a
Clarification: The disadvantage of the involute teeth is that the interference occurs. This may be avoided by altering the heights of addendum and dedendum of the mating teeth.

2. By changing the angle of obliquity of the teeth, interference can be avoided.
a) True
b) False
Answer: a
Clarification: Interference can be avoided by changing the obliquity of the teeth or alternatively altering the height of the addendum. Failure to do so will result in the occurrence of interference.

3. The phenomenon when the tip of tooth undercuts the root on its mating gear is known as _______
a) Involution
b) Interference
c) Cycloidal motion
d) Undercutting
Answer: a
Clarification: The phenomenon when the tip of tooth undercuts the root on its mating gear is known as interference. This is generally observed in involute profiles.

4. In which of the following gears, interference occurs?
a) Cycloidal
b) Involute
c) Epi cycloidal
d) Hypo-cycloidal
Answer: b
Clarification: Interference occurs in involute gears which is one of its disadvantages amongst many advantages. This happens when the pinion has a low number of teeth.

5. For the same pitch, which of the following statement is true?
a) Cycloidal gears are stronger than involute gears
b) Involute gears are stronger than cycloidal gears
c) Both cycloidal and Involute gears have equal strength
d) Cycloidal gears are stronger for lower pitch only
Answer: a
Clarification: Cycloidal teeth have wider flanks, as a consequence the cycloidal gears are stronger than the involute gears, provided the pitch is the same. That is why cycloidal gears are used for cast teeth.

6. If the point of contact between the two teeth is always on the involute profiles of both the teeth, then which of the phenomenon will occur?
a) Avoidance of interference
b) Occurrence of interference
c) Increase in length of path of contact
d) Increase in length of arc of contact
Answer: a
Clarification: The interference may only be avoided, if the point of contact between the two teeth is always on the involute profiles of both the teeth.

7. Given,
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the addendum height for the larger gear wheel in mm.
a) 6.5
b) 6
c) 6.8
d) 7
Answer: a
Clarification: r = m.t/2 = 100mm
R = 200mm
Using the constraint we find that
Ra = 206.5mm
Therefore
Addendum height = 6.5mm.

8. Given:
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the addendum height for the smaller gear wheel in mm.
a) 6.4
b) 6.2
c) 6.3
d) 6
Answer: b
Clarification: r = m.t/2 = 100mm
R = 200mm
Using the constraint we find that
ra = 106.2mm
Therefore
Addendum height = 6.2mm.

9. Given:
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the length of path of contact in mm.
a) 56.4
b) 56.2
c) 56.3
d) 51.3
Answer: d
Clarification: r = m.t/2 = 100mm
R = 200mm
We know that length of path of contact = (R+r)sinΦ/2
= 51.3mm.

10. Given:
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the length of arc of contact in mm.
a) 56.4
b) 54.6
c) 56.3
d) 51.3
Answer: b
Clarification: r = m.t/2 = 100mm
R = 200mm
We know that length of path of contact = (R+r)sinΦ/2
= 51.3mm
Arc of contact = length of path of contact / cosΦ
= 54.6mm.

11. Given:
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the contact ratio.
a) 1.23
b) 1.52
c) 1.74
d) 1.97
Answer: c
Clarification: r = m.t/2 = 100mm
R = 200mm
We know that length of path of contact = (R+r)sinΦ/2
= 51.3mm
Pitch = πx10 = 31.42
Contact ratio = length of path of contact/pitch
= 1.74.

Machine Kinematics Questions and Answers for Freshers on “Relation Between Linear Motion and Angular Motion”.

1. Which of the following disciplines provides study of inertia forces arising from the combined effect of the mass and motion of the parts?
a) theory of machines
b) applied mechanics
C) kinematics
d) kinetics
Answer: d
Clarification: The study of inertia forces arising from the combined effect of the mass and motion of the parts is called kinetics.
The study of relative motion between the parts of a machine is called kinematics.
The study of the relative motion between the parts of a machine and the forces acting on the parts is called theory of machines.

2. Which of the following disciplines provides study of relative motion between the parts of a machine?
a) theory of machines
b) applied mechanics
C) kinematics
d) kinetics
Answer: c
Clarification: The study of inertia forces arising from the combined effect of the mass and motion of the parts is called kinetics.
The study of relative motion between the parts of a machine is called kinematics.
The study of the relative motion between the parts of a machine and the forces acting on the parts is called theory of machines.

3. Which of the following disciplines provides study of the relative motion between the parts of a machine and the forces acting on the parts?
a) theory of machines
b) applied mechanics
C) kinematics
d) kinetics
Answer: a
Clarification: The study of inertia forces arising from the combined effect of the mass and motion of the parts is called kinetics.
The study of relative motion between the parts of a machine is called kinematics.
The study of the relative motion between the parts of a machine and the forces acting on the partsis called theory of machines.

4. The type of pair formed by two elements which are so connected that one is constrained to turn or revolve about a fixed axis of another element is known as
a) turning pair
b) rolling pair
c) sliding pair
d) spherical pair
Answer: a
Clarification: When 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.

5. Which of the following is a lower pair?
a) ball and socket
b) piston and cylinder
c) cam and follower
d) both a and b
Answer: d
Clarification: In both ball and socket and piston cylinder there is surface contact between the two elements. Hence, they form a lower pair.

6. If two moving elements have surface contact in motion, such pair is known as
a) sliding pair
b) rolling pair
c) surface pair
d) lower pair
Answer: d
Clarification: when two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as lower pair.

7. The example of lower pair is
a) shaft revolving in a bearing
b) straight line motion mechanisms
c) automobile steering gear
d) all of the mentioned
Answer: d
Clarification: In all the mentioned elements there is surface contact between the two elements. Hence, they form a lower pair.

8. Pulley in a belt drive acts as
a) cylindrical pair
b) turning pair
c) rolling pair
d) sliding pair
Answer: c
Clarification: When the two elements of a pair are connected in such a way that one rolls over another fixed link, the pair is known as rolling pair. In belt and pulley, the belt rolls over the pulley.

9. The example of rolling pair is
a) bolt and nut
b) lead screw of a lathe
c) ball and socket joint
d) ball bearing and roller bearing
Answer: d
Clarification: In ball bearing and roller bearing one element rolls over the other element. Hence, they are examples of rolling pair.

10. Any point on a link connecting double slider crank chain will trace a
a) straight line
b) circle
c) ellipse
d) parabola
Answer: c
Clarification: One of the inversions of a double slider crank chain is elliptical trammels. So, from the above given options ellipse is best suited.

11. The purpose of a link is to
a) transmit motion
b) guide other links
c) act as a support
d) all of the mentioned
Answer: d
Clarification: None

12. A universal joint is an example of
a) higher pair
b) lower pair
c) rolling pair
d) sliding pair
Answer: b
Clarification: In universal joint, there is surface contact between the two elements. Hence, they form a lower pair.

13. Rectilinear motion of piston is converted into rotary by
a) cross head
b) slider crank
c) connecting rod
d) gudgeon pin
Answer: b
Clarification: In single slider crank chain rotary motion is converted into reciprocating motion.

Machine Kinematics Interview Questions and Answers for Experienced people on “Simple Mechanisms – 2”.

1. The relation between the number of links (l) and the number of binary joints ( j) for a kinematic chain having constrained motion is given by j = 3/2 I -2 If the left hand side of this equation is greater than right hand side, then the chain is
a) locked chain
b) completely constrained chain
c) successfully constrained chain
d) incompletely constrained chain
Answer: a
Clarification: If the left hand side is greater than the right hand side, therefore it is not a kinematic chain and hence no relative motion is possible. Such type of chain is called locked chain and forms a rigid frame or structure which is used in bridges and trusses.

2. In a kinematic chain, a quaternary joint is equivalent to
a) one binary joint
b) two binary joints
c) three binary joints
d) four binary joints
Answer: c
Clarification: When four links are joined at the same connection, the joint is called a quaternary joint. It is equivalent to three binary joints.

3. If n links are connected at the same joint, the joint is equivalent to
a) (n – 1) binary joints
b) (n – 2) binary joints
c) (2n – 1) binary joints
d) none of the mentioned
Answer: a
Clarification: In general, when n number of links are joined at the same connection, the joint is equivalent to (n – 1) binary joints.

4. In a 4 – bar linkage, if the lengths of shortest, longest and the other two links are denoted by s, l, p and q, then it would result in Grashof’s linkage provided that
a) l + p < s + q
b) l + s < p + q
c) l + p = s + q
d) none of the mentioned
Answer: b
Clarification: None

5. A kinematic chain is known as a mechanism when
a) none of the links is fixed
b) one of the links is fixed
c) two of the links are fixed
d) all of the links are fixed
Answer: b
Clarification: When one of the links of a kinematic chain is fixed, the chain is known as mechanism. It may be used for transmitting or transforming motion e.g. engine indicators, typewriter etc.

6. The Grubler’s criterion for determining the degrees of freedom (n) of a mechanism having plane motion is
a) n = (l – 1) – j
b) n = 2 (l – 1) – 2j
c) n = 3 (l – 1) – 2j
d) n = 4 (l – 1) – 3j
Answer: c
Clarification: The Grubler’s criterion applies to mechanisms with only single degree of freedom joints where the overall movability of the mechanism is unity.
i.e. n = 3 (l – 1) – 2j
where l = Number of links, and j = Number of binary joints.

7. The mechanism forms a structure, when the number of degrees of freedom (n) is equal to
a) 0
b) 1
c) 2
d) – 1
Answer: a
Clarification: When n = 0, then the mechanism forms a structure and no relative motion between the links is possible.
When n = 1, then the mechanism can be driven by a single input motion.
When n = 2, then two separate input motions are necessary to produce constrained motion for the mechanism.
When n = – 1 or less, then there are redundant constraints in the chain and it forms a statically indeterminate structure.

8. In a four bar chain or quadric cycle chain
a) each of the four pairs is a turning pair
b) one is a turning pair and three are sliding pairs
c) three are turning pairs and one is sliding pair
d) each of the four pairs is a sliding pair.
Answer: a
Clarification: A very important consideration in designing a mechanism is to ensure that the input crank makes a complete revolution relative to the other links. The mechanism in which no link makes a complete revolution will not be useful. In a four bar chain, one of the links, in particular the shortest link, will make a complete revolution relative to the other three links, if it satisfies the Grashof ’s law. Such a link is known as crank or driver.

9. Which of the following is an inversion of single slider crank chain ?
a) Beam engine
b) Watt’s indicator mechanism
c) Elliptical trammels
d) Whitworth quick return motion mechanism
Answer: d
Clarification: None

10. Which of the following is an inversion of double slider crank chain ?
a) Coupling rod of a locomotive
b) Pendulum pump
c) Elliptical trammels
d) Oscillating cylinder engine
Answer: c
Clarification: A kinematic chain which consists of two turning pairs and two sliding pairs is known as double slider crank chain and elliptical trammels are such pairs.