Engineering Questions with Answers - Multiple Choice Questions

# Machine Kinematics Questions and Answers – Types of Kinematic Chains

1 - Question

Scotch yoke mechanism is used to generate
a) Sine functions
b) Square roots
c) logarithms
d) inversions

Explanation: In Scotch Yoke mechanism, the constant rotation of the crank produces harmonic translation of the yoke. Its four binary links are:
2. Crank
3. Sliding Block
4. Yoke.

2 - Question

Which of the following are inversions of a double slider crank chain?
1. Whitworth return motion 2. Scotch Yoke
3. Oldham’s Coupling 4. Rotary engine
Select correct answer using the codes given below:
Codes:
a) 1 and 2
b) 1, 3 and 4
c) 2 and 3
d) 2, 3 and 4

Explanation: Double slider crank mechanism
It has four binary links, two revolute pairs, two sliding pairs. Its various types are:
1. Scotch Yoke mechanism
2. Oldhams Coupling
3. Elliptical Trammel.

3 - Question

Oldham’s coupling is used to transmit power between two parallel shafts which are slightly offset.
a) True
b) false

Explanation: It is used for transmitting angular velocity between two parallel but eccentric shafts.

4 - Question

In Oldham’s coupling the condition for maximum speed ratio is
a) w1cosα/W
b) w1sinα/W
c) w1/W = 1/cosα
d) w1/W = 1/sinα

Explanation: w1/W = cosα/1 – cos2ϴsin2α
For maximum speed ratio cos2ϴ = 1
Therefore, w1/W = 1/cosα.

5 - Question

The relative acceleration of two points which are at variable distance apart on a moving link can be determined by using the
a) three centers in line theorem
b) instantaneous centre of rotation method
c) Coriolis component of acceleration method
d) Klein’s construction

Explanation: The relative acceleration of two variable points on a moving link can be determined by using the instantaneous centre of rotation method.

6 - Question

What is the number of instantaneous centres of rotation for a 6-link mechanism?
a) 4
b) 6
c) 12
d) 15

Explanation: N = n(n – 1)/2 = 6 x (6 – 1)/2 = 15.

7 - Question

For one degree of freedom planer mechanism having links, which one of the following is the possible combination?

Explanation: From Grubler’s criteria 1 = 3(l – 1) – 2j
or, j = 3/2l – 2 for six link
j = 3/2 x 6 – 2 = 7 1 ternary link = 2 binary link
a) j = 4 + 2 x 2 ≠ 7
b) j = 4 x 2 + 2 ≠ 7
c) j = 3 x 2 + 2 ≠ 7
d) j = 1 x 2 + 5 ≠ 7 the ans is d.

8 - Question

Inversion of a kinematic chain relative to some other links is a property of the chain and is not that of the mechanism.
a) True
b) False

Explanation: In a kinematic inversion relative motion does not change but absolute motion change drastically.

9 - Question

In a shaping operation, the average cutting speed is ( Stroke length S, Number of strokes per minute N, Quick return ratio R)
a) NSR
b) NSR/2
c) NS(1 + R)
d) NS(1 + R)/2

Explanation: Time for forward stroke + Tf
Time for return stroke = Tr
R = Tr/Tf
Therefore, time for only one cutting stroke(T) = 1/N x Tf/(Tf + Tr)
Average cutting speed = S/T = SN(Tf + Tr)/Tf = SN(1 + R).

10 - Question

Ina kinematic inversion, the relative motions between links of the mechanism change as different links are made the frame by turns.
a) True
B) False

Explanation: Through the process of inversion the relative motions between the various links is not changed in any manner but their absolute motions may be changed drastically.

11 - Question

An elliptical trammel is a mechanism with three prismatic pairs and one revolute pair.
a) True
B) False