Kinematics of Machinery Questions and Answers Part-20

1. 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: b
Explanation: 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.

2. The method of obtaining different mechanisms by fixing in turn different links in a kinematic chain, is known as
a) structure
b) machine
c) inversion
d) compound mechanism

Answer: c
Explanation: We can obtain as many mechanisms as the number of links in kinematic chain by fixing, in turn,different links in a kinematic chain. This method is known as inversion of the mechanism.

3. If the number of links in a mechanism are equal to l, then the number of possible inversions are equal to
a) l – 2
b) l – 1
c) 1
d) l + 1

Answer: c
Explanation: Whatever is the number of links in a mechanism, only that much number of inversion can be obtained.

4. Which of the following statement is correct as regard to the difference between a machine and a structure?
a) The parts of a machine move relative to one another, whereas the members of a structure do not move relative to one another.
b) The links of a machine may transmit both power and motion, whereas the members of a structure transmit forces only.
c) A machine transforms the available energy into some useful work, whereas in a structure no energy is transformed into useful work.
d) all of the mentioned

Answer: d
Explanation: all of the mentioned

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) none of the mentioned

Answer: b
Explanation: When one of the links of a kinematic chain is fixed, the chain is known as mechanism.

6. The inversion of a mechanism is
a) changing of a higher pair to a lower pair
b) turning its upside down
c) obtained by fixing different links in a kinematic chain
d) obtained by reversing the input and output motion

Answer: c
Explanation: We can obtain as many mechanisms as the number of links in kinematic chain by fixing, in turn,different links in a kinematic chain. This method is known as inversion of the mechanism.

7. 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
Explanation: n = 3(l – 1) – 2j

8. 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
Explanation: A structure can be formed only when the number of degrees of freedom is zero.

9. 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) two are turning pairs and two are sliding pairs
d) three are turning pairs and one is a sliding pair

Answer: a
Explanation: Four bar chain or quadric cycle chain consists of four links, each of them forms a turning pair.

10. The mechanism in which two are turning pairs and two are sliding pairs, is called a.
a) double slider crank chain
b) elliptical trammel
c) scotch yoke mechanism
d) all of the mentioned

Answer: d
Explanation: A double slider crank chain consists of two sliding pairs and two turning pairs. The inversions of a double slider crank chain are as follows:
a) elliptical trammel
b) scotch yoke mechanism
c) oldham’s coupling