Category: Machine Kinematics Objective Questions

Machine Kinematics Multiple Choice Questions on “Gear Trains”.

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
Clarification: 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
Clarification: 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
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.
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
Clarification: 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
Clarification: 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
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. 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
Clarification: 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
Clarification: 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
a) addendum
b) dedendum
c) addendum + dedendum
d) 2 x addendum
Answer: d
Clarification: 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
Clarification: Tooth thickness = 1.5708 x module.

Machine Kinematics Multiple Choice Questions on “Reverted Gear Train”.

1. Gearing contact is which one of the following?
a) Sliding contact
b) Sliding contact, only rolling at pitch point
c) Rolling contact
d) Rolling and sliding at each point of contact
Answer: b
Clarification: When pair of teeth touch at the pitch point ,they have for the instant pure rolling action. At any other position they have the sliding action.

2. An external gear with 60 teeth meshes with a pinion of 20 teeth, module being 6 mm. What is the centre distance in mm?
a) 120
b) 180
c) 240
d) 300
Answer: c
Clarification: Centre distance in mm = m/2 (T₁ + T₂)
= 6/2 (60 + 20)
= 240 mm

3. Which one of the following is true for involute gears?
a) Interference is inherently absent
b) Variation in centre distance of shafts increases radial force
c) A convex flank is always in contact with concave flank
d) Pressure angle is constant throughout the teeth engagement
Answer: d
Clarification: For involute gears, the pressure angle is constant throughout the teeth engagement.

4. In involute gears the pressure angle is
a) Dependent on the size of teeth
b) dependent on the size of gears
c) Always constant
d) always variable
Answer: c
Clarification: The pressure angle is always constant in involute gears.

5. Consider the following statements:
1. A stub tooth has a working depth larger than that of a full-depth tooth.
2. The path of contact for involute gears is an arc of a circle.
Which of the statements given above is/are correct?
a) Only 1
b) Only 2
c) Both 1 and 2
d) Neither 1 nor 2
Answer: d
Clarification: 1. A stub tooth has a working depth lower than that of a full-depth tooth.
2. The path of contact for involute gears is a line.

6. Consider the following statements regarding the choice of conjugate teeth for the profile of mating gears:
1. They will transmit the desired motion
2. They are difficult to manufacture.
3. Standardisation is not possible
4. The cost of production is low.
Which of these statements are correct?
a) 1, 2 and 3
b) 1, 2 and 4
c) 2, 3 and 4
d) 1, 3 and 4
Answer: a
Clarification: Cost of production of conjugate teeth, being difficult to manufacture is high.

7. Common contact ratio of a pair of spur pinion and gear is
a) Less than 1·0
b) Equal to 1
c) Between 2 and 3
d) Greater than 3
Answer: c
Clarification: The ratio of the length of arc of contact to the circular pitch is known as contact ratio i.e. number of pairs of teeth in contact. The contact ratio for gears is greater than one. Contact ratio should be at least 1.25. For maximum smoothness and quietness, the contact ratio should be between 1.50 and 2.00. High-speed applications should be designed with a face-contact ratio of 2.00 or higher for best results.

8. In gears, interference takes place when
a) The tip of a tooth of a mating gear digs into the portion between base and root circles
b) Gears do not move smoothly in the absence of lubrication
c) Pitch of the gear is not same
d) gear teeth are undercut
Answer: a
Clarification: In gears, interference takes place when the tip of a tooth of a mating gear digs into the portion between base .and root circle.

9. Consider the following characteristics:
1. Small interference
2. Strong tooth.
3. Low production cost
4. Gear with small number of teeth.
Those characteristics which are applicable to stub 20° involute system would include
a) 1 alone
b) 2, 3 and 4
c) 1, 2 and 3
d) 1, 2, 3 and 4
Answer: b
Clarification: Involute system is very interference prone.

10. A spur gear transmits 10 kW at a pitch line velocity of 10 m/s; driving gear has a diameter of 1.0 m. Find the tangential force between the driver and the follower, and the transmitted torque respectively.
a) 1 kN and 0.5 kN-m
b) 10 kN and 5 kN-m
c) 0.5 kN and 0.25 kN-m
d) 1 kN and 1 kN-m
Answer: a
Clarification: Power transmitted = Force × Velocity
Force = 10 x 10³/10
= 1000 N/m
Torque Transmitted = Force x diameter/2
= 1000 x 1/2
= 500 N-m
= 0.5 kN-m

Machine Kinematics Interview Questions and Answers on “Linear Velocity – 2”.

1. The unit of linear acceleration is
a) kg-m
b) m/s
c) m/s²
d) rad/s²
Answer: c
Clarification: Linear acceleration, a = dv/dt
unit of dv = m/s
and dt = s
therefore, dv/dt = m/s²

2. The angular velocity (in rad/s) of a body rotating at N r.p.m. is
a) π N/60
b) 2 π N/60
c) π N/120
d) π N/180
Answer: b
Clarification: Angular velocity may be defined as the rate of change of angular displacement with respect to time. It is usually expressed by a Greek letter ω (omega). Mathematically, angular velocity,
ω =dθ/dt

3. The linear velocity of a body rotating at ω rad/s along a circular path of radius r is given by
a) ω.r
b) ω/r
c) ω².r
d) ω²/r
Answer: a
Clarification: Linear velocity = ω.r

4. When a particle moves along a straight path, then the particle has
a) tangential acceleration only
b) centripetal acceleration only
c) both tangential and centripetal acceleration
d) none of the mentioned
Answer: a
Clarification: When a particle moves along a straight path, then the radius of curvature is infinitely great. This means that v²/r is zero. In other words, there will be no normal or radial or centripetal acceleration. Therefore, the particle has only tangential acceleration.

5. When a particle moves with a uniform velocity along a circular path, then the particle has
a) tangential acceleration only
b) centripetal acceleration only
c) both tangential and centripetal acceleration
d) none of the mentioned
Answer: b
Clarification: When a particle moves with a uniform velocity, then dv/dt will be zero. In other words, there will be no tangential acceleration; but the particle will have only normal or radial or centripetal acceleration.

6. When the motion of a body is confined to only one plane, the motion is said to be
a) translatory motion
b) plane motion
c) culvilinear motion
d) none of the mentioned
Answer: b
Clarification: When the motion of a body is confined to only one plane, the motion is said to be plane motion. When the motion of a body is along a straight line path, it is called translatory motion. When the motion of a body is along a curved path, it is called culvilinear motion.

7. When the motion of a body is along a straight line path, it is called
a) translatory motion
b) plane motion
c) culvilinear motion
d) none of the mentioned
Answer: b
Clarification: When the motion of a body is confined to only one plane, the motion is said to be plane motion. When the motion of a body is along a straight line path, it is called translatory motion. When the motion of a body is along a curved path, it is called culvilinear motion.

8. When the motion of a body is along a curved path, it is called
a) translatory motion
b) plane motion
c) culvilinear motion
d) none of the mentioned
Answer: b
Clarification: When the motion of a body is confined to only one plane, the motion is said to be plane motion. When the motion of a body is along a straight line path, it is called translatory motion. When the motion of a body is along a curved path, it is called culvilinear motion.

Machine Kinematics Multiple Choice Questions on “Inversions of Four Bar Chain”.
1. Match list I with list II
List I List II
A. Quick return mechanism 1. Lathe
B. Apron mechanism 2. Milling machine
C. Indexing mechanism 3. Shaper
D. Regulating wheel 4. Centreless grinding

a) A-3,B-2,C-1,D-4
b) A-2,B-3,C-4,D-1
c) A-4,B-2,C-3,D-1
d) A-3,B-1,C-2,D-4
Answer: d
Clarification: Quick return mechanism – Shaper
Apron mechanism – Lathe
Indexing mechanism – Milling machine
Regulating wheel – Centreless grinding

2. A point on a link connecting a double slider crank chain will trace a
a) straight line
b) circle
c) parabola
d) ellipse
Answer: d
Clarification: The point on connecting link traces an elliptical path.

3. A wheel is rolling on a straight level track with a uniform velocity ‘v’. The instantaneous velocity of a point on the wheel lying at the mid-point of a radius
a) varies between 3 v/2 and -v/2
b) varies between v/2 and -v/2
c) varies between 3 v/2 and -v/2
d) does not vary and is equal to v
Answer: b
Clarification: None

4. A four-bar chain has
a) all turning pairs
b) one turning pair and the others are sliding pairs
c) one sliding pair and the others are turning pairs
d) all sliding pairs
Answer: a
Clarification: A four-bar linkage, also called a four-bar, is the simplest movable closed chain linkage. It consists of four bodies, called bars or links, connected in a loop by four joints. Generally, the joints are configured so the links move in parallel planes, and the assembly is called a planar four-bar linkage.

5. The mechanism in a shaping machine is
a) a closed 4-bar chain having 6 revolute pairs
b) a closed 6-bar chain having 6 revolute pairs
c) a closed 4-bar chain having 2 revolute and 2 sliding pairs
d) an inversion of single slider crank chain
Answer: d
Clarification: Shaping machines use quick return mechanism which are either Whitworth quick return mechanism or crank and slotted lever quick return mechanism. These are inversions of single slider crank chain.

6. The number of inversions of a slider crank chain is
a) 6
b) 5
c) 4
d) 3
Answer: c
Clarification: A slider crank chain has 4 links and by fixing each link, one at a time, we get 4 different mechanisms, each of which is an inversion. Hence, a slider crank chain has 4 inversions.

7. Which of the following is an inversion of single slider crank chain?
a) Elliptical Trammel
b) Hand Pump
c) Oldham’s Coupling
d) Scotch Yoke
Answer: b
Clarification: Hand pump is an inversion of single slider crank chain.

8. Which of the following are the inversions of double slider crank chain?
1. Oldhan coupling
2. Whitworth quick return mechanism
3. Beam engine mechanism
4. Elliptical Trammel mechanism
The correct answer codes are
a) 1 and 2
b) 1 and 4
c) 2, 3 and 4
d) 1, 2 and 3
Answer: b
Clarification: Oldham coupling and Elliptical trammel are inversions of double slider crank chain.
Whitworth quick return mechanism is an inversion of single slider crank chain. Beam engine mechanism is an inversion of 4-bar linkage.

9. Which of the following is an inversion of single slider crank chain?
a) Beam engine
b) Watt’s indicator mechanism
c) Elliptical Trammel
d) Oscillating cylinder engine
Answer: d
Clarification: Oscillating cylinder engine is an inversion of single slider crank chain.

10. Oldham’s coupling is used to connect two shafts which are
a) intersecting
b) parallel
c) perpendicular
d) co-axial
Answer: b
Clarification: Oldham’s coupling is used to connect slightly offset parallel shafts.

Machine Kinematics Objective Questions & Answers on “Acceleration in the Slider Crank Mechanism & Coriolis Component”.

1. A point is moving at the end of the link rotating with constant angular velocity ω, what will be the value of tangential component of acceleration?
a) 0
b) ω²R
c) Infinite
d) ω²R/2
Answer: a
Clarification: Any point at the end of the link which is moving with a constant angular velocity has no component as tangential acceleration, it only possesses radial component of acceleration.

2. The tangential component of acceleration is maximum when the link rotates with a constant angular velocity.
a) True
b) False
Answer: b
Clarification: The tangential component of acceleration is zero when the link is rotating with a constant angular velocity, hence the given statement is false.

3. A point is moving at the end of the link rotating with constant angular velocity ω, what will be the value of radial component of acceleration?
a) 0
b) ω²R
c) Infinite
d) ω²R/2
Answer: b
Clarification: Any point at the end of the link which is moving with a constant angular velocity has no component as tangential acceleration, it only possess radial component of acceleration whose value is given by ω²R, where R is the distance of the point from the reference point.

4. In a slider crank mechanism, the crank rotates with a constant angular velocity of 300 rpm, Length of crank is 150mm, and the length of the connecting rod is 600mm. Determine linear velocity of the midpoint of the connecting rod in m/s. Crank angle = 45° from IDC.
a) 4.1
b) 4.4
c) 4.8
d) 5.2
Answer: a
Clarification: Let the Intersection point of crank and connecting rod be termed as ‘x’
velocity of x = ωxL(crank)
= 4.713 m/s
We draw a corresponding velocity diagram for the same,
where this velocity is perpendicular to the crank, this diagram when drawn to scale turns out to be a triangle.
From the reference point we can measure the velocity of midpoint of connecting rod
V = 4.1 m/s.

5. In a slider crank mechanism, the crank rotates with a constant angular velocity of 300 rpm, Length of crank is 150mm, and the length of the connecting rod is 600mm. Determine acceleration of the midpoint of the connecting rod in m/s². Crank angle = 45° from IDC.
a) 117
b) 144
c) 148
d) 252
Answer: a
Clarification: Let the Intersection point of crank and connecting rod be termed as ‘x’
velocity of x = ωxL(crank)
= 4.713 m/s
We draw a corresponding velocity diagram for the same,
where this velocity is perpendicular to the crank, this diagram when drawn to scale turns out to be a triangle.
From the reference point we can measure the velocity of midpoint of connecting rod V = 4.1 m/s
From the acceleration diagram of the same , we find that acceleration of midpoint of the connecting rod comes out to be
117m/s².

6. What will be the shape of the velocity diagram of the slider crank mechanism if there are three links including the slider.
a) Triangle
b) Parallelogram
c) Square
d) Trapezium
Answer: a
Clarification: When there are two links and a slider in a slider crank mechanism, there are in total 3 links. In this case the shape of the velocity polygon is a triangle.

7. If the normal component of the acceleration is doubled, what will be the effect on the radial component?
a) Doubled
b) Halved
c) Remains same
d) Becomes 4 times
Answer: a
Clarification: The component which is normal to the motion is known as the normal component which comes from the angular velocity, this is also known as the radial component. Hence radial and normal components are the same.

8. If the body is not rotating with a constant angular velocity then there are both radial and tangential component of acceleration.
a) True
b) False
Answer: a
Clarification: The radial component always exists as long as the body is rotating with some angular velocity, however the tangential components acts only if the angular velocity is not constant. In this case both the components will act on the given link.

9. In the given figure, the direction of radial velocity vector and angular velocity is given what will be the direction of coriolis force?

a) Along the radial velocity vector
b) Opposite to radial velocity vector
c) Perpendicular to radial velocity vector towards right
d) Perpendicular to radial velocity vector towards left
Answer: d
Clarification: The direction of the coriolis component of acceleration is obtained by rotating the radial velocity vector by 90 degrees in the direction of the angular velocity.

10. Coriolis component of acceleration exists when there is relative motion between two points from the ground frame.
a) True
b) False
Answer: a
Clarification: When there is relative motion between two points from the ground frame, Pseudo force exists.

11. Calculate the coriolis component of acceleration in m/s² from the following data:
ω = 12 rad/s
v = 2 m/s
R = 1 m
a) 24
b) 12
c) 36
d) 6
Answer: a
Clarification: The coriolis component of acceleration is given by
2ωV
inserting the values we get
a = 24 m/s².

12. Which component of acceleration is parallel to the given link?
a) Radial
b) Tangential
c) Coriolis
d) Pseudo
Answer: a
Clarification: The radial component also known as the normal component is parallel to the link and always exists as long as there is angular velocity.

13. Which of the following mechanism will have coriolis component?
a) Quick return motion mechanisms
b) Slider crank mechanism
c) Four bar chains
d) Gnome engine
Answer: a
Clarification: Quick return motion mechanism have sliders attached to the link, hence out of the given options quick return motion mechanisms will have coriolis component of acceleration.

14. Which component of acceleration is parallel to the velocity of given link?
a) Radial
b) Tangential
c) Coriolis
d) Pseudo
Answer: b
Clarification: The radial component also known as the normal component is parallel to the link and always exists as long as there is angular velocity. However the tangential component acts in a direction parallel to the velocity of the link.

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