Multiple choice question for engineering
Set 1
1. The number of degrees of freedom of a planer linkage with 8 links and 9 simple revolute joints is
a) 1
b) 2
c) 3
d) 4
Answer
Answer: c [Reason:] No. of links, I = 8
No. of revolute joints, J = 9
No. of higher pair, h = 0
Number of degree of freedom, n = 3(I -1) – 2j – h
= 3(8 – 1) – 2×9 – 0 = 3.
2. A palnar mechanism has 8 links and 10 rotary joints. The number of degrees of freedom of the mechanism, using Grubler’s criterion, is
a) 0
b) 1
c) 2
d) 3
Answer
Answer: b [Reason:] Whatever may be the number of links and joints Grubler’s criterion applies to mechanism with only single degree freedom. Subject to the condition 3I – 2J – 4 = 0 and it satisfy this condition.
Degree of freedom is given by = 3(I – 1) – 2j = 3(8 -1) – (2×10) = 1.
3. Match the approaches given below to perform stated kinematics/dynamics analysis of machine.
Analysis Approach
P. Continuous relative rotation 1. D’Alembert’s principle
Q. Velocity and acceleration 2. Grubler’s criterion
R. Mobility 3. Grashof’s law
S. Dynamic-static analysis 4. Kennedy’s theorem
a) P-1,Q-2,R-3,S-4
b) P-3,Q-4,R-2,S-1
c) P-2,Q-3,R-4,S-1
d) P-4,Q-2,R-1,S-3
Answer
Answer: b [Reason:]
1. D’Alembert’s principle – Dynamic-static analysis
2. Grubler’s criterion – Mobility(for a plane mechanism)
3. Grashof’s law – Continuous relative rotation
4. Kennedy’s theorem – Velocity and acceleration.
4. Which of the following statements is incorrect
a) Grashof’s rule states that for a planar crank-rocker four bar mechanism, the sum of the shortest and longest link lengths cannot be less than the sum of the remaining two link lengths.
b) Inversions of a mechanism are created by fixing different links one at a time.
c) Geneva mechanism is an intermittent motion device.
d) Gruebler’s criterion assumes mobality of a planar mechanism to be one.
Answer
Answer: a [Reason:] According to Grashof’s rule for complete relative rotation r/w links L + S < p + q.
5. In a four bar linkage, s denotes the shortest link length, L is the longest link length, P and Q are the lengths of other two links. At least one of the three moving links will rotate by 360° if
a) S + L < P + Q
b) S + L > P + Q
c) S + P < L + Q
d) S + P > L + Q
Answer
Answer: a [Reason:] According to Grashof’s law for four bar mechanism, the sum of shortest and longest link lengths should not be greater than the sum of remaining two link length.
i.e. S + L < P + Q.
6. The number of inversions for a slider crank mechanism is
a) 6
b) 5
c) 4
d) 3
Answer
Answer: c [Reason:] No. of links of a slider crank mechanism = 4
So there are four inversion of slider crank mechanism.
7. The mechanism used in a shaping machine is
a) A closed 4bar chain having 4 revolute pairs
b) A closed 6bar chain having 6 revolute pairs
c) A closed 4bar chain having 2 revolute and 2 sliding pairs
d) An inversion of single slider crank chain
Answer
Answer: d [Reason:] Quick return mechanism.
8. Match the following
Types of mechanism Motion achieved
P. Scott Russel mechanism 1. Intermittent motion
Q. Geneva mechanism 2. Quick return motion
R. Off set slider crank mechanism 3. Simple harmonic motion
S. scotch Yoke mechanism 4. Straight line motion
a) P-2,Q-3,R-1,S-4
b) P-3,Q-2,R-4,S-1
c) P-4,Q-1,R-2,S-3
d) P-4,Q-3,R-1,S-2
Answer
Answer: c [Reason:]
1. Intermittent motion – Geneva mechanism
2. Quick return motion – Off set slider crank mechanism
3. Simple harmonic motion – scotch Yoke mechanism
4. Straight line motion – Scott Russel mechanism.
9. In a kinematic chain, a quaternary joint is equivalent to
a) one binary joint
b) two binary joint
c) three binary joint
d) four binary joint
Answer
Answer: c [Reason:] When ‘l’ number of links are joined at the same connection, the joint is equivalent to (l – 1) binary joints.
10. When supported on three points, out of 12 degrees of freedom the number of degrees of freedom arrested in a body is
a) 3
b) 4
c) 5
d) 6
Answer
Answer: d [Reason:] When supported on three points, following six degrees of freedom are arrested.
Set 2
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
Answer: d [Reason:] 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
Answer: d [Reason:] 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
Answer: b
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
Answer: a [Reason:] 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
Answer: d [Reason:] 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
Answer: c [Reason:] 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
Answer: b [Reason:] 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
Answer: b [Reason:] 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
Answer: d [Reason:] 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
Answer: b [Reason:] Oldham’s coupling is used to connect slightly offset parallel shafts.
Set 3
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 (l – 2). If the left hand side of this equation is greater than the right hand side, then the chain is
a) locked chain
b) completely constrained chain
c) successfully constrained chain
d) incompletely constrained chain
Answer
Answer: a [Reason:] If the L.H.s. > R.H.S., then the chain is called a locked chain and forms a 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
Answer: c [Reason:] When four links are joined at the same connection, the joint is called a quaternary joint. It is equivalent to three binary joints.
3. A chain consisting of four links and four joints is called a kinematic chain.
a) True
b) False
Answer
Answer: a [Reason:] A kinematic chain is 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.
4. In a steam engine, the link constitutes a
a) piston, piston rod and cross-head
b) connecting rod with big and small end brasses, caps and bolts
c) crank pin, crankshaft and flywheel
d) all of the mentioned
Answer
Answer: d
5. A mechanism is a assemblage of
a) two links
b) three links
c) four or more than four links
d) all of the mentioned
Answer
Answer: c [Reason:] When one of the links of a kinematic chain is fixed, the chain is known as mechanism. A simple mechanism consists of minimum four links.
6. A mechanism consisting more than four links is called a compound mechanism.
a) True
b) False
Answer
Answer: a [Reason:] A mechanism with four links is known as simple mechanism, and the mechanism with more than four links is known as compound mechanism.
7. A mechanism consisting of four links is called a _____________ mechanism.
a) simple
b) compound
c) inversion
d) none of the mentioned
Answer
Answer: a [Reason:] A mechanism with four links is known as simple mechanism, and the mechanism with more than four links is known as compound mechanism.
8. A mechanism ______________ for transmitting or transforming motion.
a) can be used
b) can not be used
c) both of the mentioned
d) none of the mentioned
Answer
Answer: a [Reason:] A mechanism is used for transmitting or transforming motion e.g. engine indicators, typewriter etc.
9. When a mechanism is required to transmit power or to do some particular type of work, then it becomes a machine.
a) True
b) False
Answer
Answer: a [Reason:] When a mechanism is required to transmit power or to do some particular type of work, then it becomes a machine. In such cases, the various links or elements have to be designed to withstand the forces safely.
10. When one of the links of a kinematic chain is fixed, the chain is known as a
a) structure
b) mechanism
c) inversion
d) machine
Answer
Answer: b [Reason:] 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.
Set 4
1. In a reciprocating steam engine, which of the following forms a kinematic link?
a) cylinder and piston
b) piston and connecting rod
c) crankshaft and flywheel
d) flywheel and engine frame
Answer
Answer: c [Reason:] Each part of a machine which moves relative to some other part, is known as a kinematic link. The piston and cylinder in a steam engine, form a pair and the motion of the piston is limited to a definite direction relative to the cylinder irrespective of the direction of motion of the crank.
2. A link or element need not to be a rigid body, but it must be a resistant body.
a) True
b) False
Answer
Answer: a [Reason:] A body is said to be a resistant body if it is capable of transmitting the required forces with negligible deformation. A link or element need not to be a rigid body, but it must be a resistant body.
3. A railway bridge is an example of a machine.
a) True
b) False
Answer
Answer: b [Reason:] When a mechanism is required to transmit power or to do some particular type of work, then it becomes a machine. A railway bridge remains static and there is no motion in it. Hence, it is not a machine.
4. The motion between a pair when limited to a definite direction, irrespective of the direction of force applied, is known as
a) completely constrained motion
b) incompletely constrained motion
c) successfully constrained motion
d) none of the mentioned
Answer
Answer: a [Reason:] When the motion between a pair is limited to a definite direction irrespective of the direction of force applied, then the motion is said to be a completely constrained motion.
5. The motion between a pair which takes place in ____________ is known as incompletely constrained motion.
a) one direction only
b) more than one direction
c) opposite direction
d) none of the mentioned
Answer
Answer: b [Reason:] When the motion between a pair can take place in more than one direction, then the motion is called an incompletely constrained motion.
6. When the connection between the elements forming a pair is such that the constrained motion is not completed by itself, but by some other means, the motion is said to be a completely constrained motion.
a) True
b) False
Answer
Answer: b [Reason:] When the motion between a pair is limited to a definite direction irrespective of the direction of force applied, then the motion is said to be a completely constrained motion.
When the connection between the elements forming a pair is such that the constrained motion is not completed by itself, but by some other means, the motion is said to be a successfully constrained motion.
7. The example of completely constrained motion is
a) motion of a piston in the cylinder of a steam engine
b) motion of a square bar in a square hole
c) motion of a shaft with collars at each end in a circular hole
d) all of the mentioned
Answer
Answer: d [Reason:] When the motion between a pair is limited to a definite direction irrespective of the direction of force applied, then the motion is said to be a completely constrained motion. In all the above mechanism, motion is limited, so they all are examples of completely constrained motion.
8. The motion of a shaft in a circular hole is an example of
a) completely constrained motion
b) incompletely constrained motion
c) successfully constrained motion
d) none of the mentioned
Answer
Answer: b [Reason:] When the motion between a pair can take place in more than one direction, then the motion is called an incompletely constrained motion. A circular bar or shaft in a circular hole, is an example of an incompletely constrained motion as it may either rotate or slide in a hole.
9. The example of successfully constrained motion is a
a) motion of an I.C. engine valve
b) motion of the shaft between a foot-step bearing
c) piston reciprocating inside an engine cylinder
d) all of the mentioned
Answer
Answer: d [Reason:] When the connection between the elements forming a pair is such that the constrained motion is not completed by itself, but by some other means, the motion is said to be a successfully constrained motion. so, the above examples have successfully constrained motion.
10. Which of the following statement is wrong?
a) A round bar in a round hole form a turning pair
b) A square bar in a square hole form a sliding pair
c) A vertical shaft in a foot step bearing forms a successful constraint
d) All of the mentioned
Answer
Answer: c
Set 5
1. When the two elements of a pair have _____________ when in motion, it is said to a lower pair.
a) line or point contact
b) surface contact
c) permit relative motion
d) none of the mentioned
Answer
Answer: b [Reason:] When the two elements of a pair have 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. It will be seen that sliding pairs, turning pairs and screw pairs form lower pairs.
2. The two elements of a pair are said to form a higher pair, when they
a) have a surface contact when in motion
b) have a line or point contact when in motion
c) are kept in contact by the action of external forces, when in motion
d) permit relative motion
Answer
Answer: b [Reason:] 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, then the pair is known as higher pair.
3. In a force-closed pair, the two elements of a pair are not held together mechanically.
a) True
b) False
Answer
Answer: b [Reason:] When the two elements of pair are not connected mechanically but are kept in contact by the action of external forces, the pair is said to be a forced-closed pair.
4. The two elements of a pair are said to form a ___________ when they permit relative motion between them.
a) open pair
b) kinematic pair
c) higher pair
d) lower pair
Answer
Answer: b [Reason:] The two links or elements of a machine, when in contact with each other, are said to form a pair. If the relative motion between them is completely or successfully constrained, the pair is known as kinematic pair.
5. In an open pair, the two elements of a pair
a) have a surface contact when in motion
b) have a line or point contact when in motion
c) are kept in contact by the action of external forces, when in motion
d) are not held mechanically
Answer
Answer: d [Reason:] When the two elements of a pair are not held mechanically, they are called open pair.
6. The sliding pairs, turning pairs and screw pairs form lower pairs.
a) True
b) False
Answer
Answer: a [Reason:] When the two elements of a pair have 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. It will be seen that sliding pairs, turning pairs and screw pairs form lower pairs.
7. 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
Answer: c [Reason:] A kinematic chain is 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.
8. The relation between 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
Answer: c [Reason:] If each link is assumed to form two pairs with 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 = 2p – 4
9. The relation between number of links(l) and number of joints(j) in a kinematic chain is
a) l = 1/2 (j+2)
b) l = 2/3 (j+2)
c) l = 3/4 (j+2)
d) l = j+4
Answer
Answer: b [Reason:] Another relation between the number of links (l) and the number of joints(j) which constitute a kinematic chain is given by the expression : l = 2/3 (j+2)
10. The relation l = 2/3(j+2) apply to kinematic chains in which lower pairs are used. This may be used to kinematic chains in which higher pairs are used, but each higher pair may be taken as equivalent to
a) one lower pair and two additional links
b) two lower pairs and one additional link
c) two lower pairs and two additional links
d) all of the mentioned
Answer
Answer: b