This set of Machine Kinematics Multiple Choice Questions & Answers (MCQs) focuses on “Single Slider Crank Chain and its Inversions”.
1. The quick return mechanism which is an inversion of 4-bar linkage is
a) Drag link mechanism
b) Whitworth quick return mechanism
c) Crank and slotted lever mechanism
d) None of the mentioned
Explanation: Drag link mechanism is an inversion of 4-bar linkage, which is a crank mechanism with different crank lengths. It is made up of revolute pairs only.
2. Match list I with list II
List I List II
A. Pantograph 1. Scotch yoke mechanism
B. Single slider crank 2. Double lever mechanism
C. Double slider crank chain 3. Tchebicheff’s mechanism
D. Straight line motion mechanism 4. Double crank
5. Hand pump
Explanation: Pantograph is double lever mechanism. handpump is an inversion of single slider crank chain. Scotch yoke mechanism is an inversion of double slider crank chain.Tchebiceff’s mechanism is an approximate straight line motion mechanism.
3. Match list I with list II
List I List II
A. Scott-Russel 1. Intemittent mechanism motion
B. Geneva 2. Quick return mechanism motion
C. Offset slider crank 3. Simple motion harmonic mechanism
D. Scotch Yoke 4. Straight line mechanism motion
Explanation: Scott-Russel – Straight line mechanism motion
Geneva – Intemittent mechanism motion
Offset slider crank – Quick return mechanism motion
Scotch Yoke – Simple motion harmonic mechanism.
4. When a cylinder is located in a Vee-block, the number of degrees of freedom which are arrested is
Explanation: Before placement on Vee-block, cylinder has 6 degrees of freedom. After placement on Vee-block, the cylinder has only 2 degrees of freedom. Hence, the degrees of freedom which are arrested is 6 – 2 = 4.
5. Match list I with list II
Type of joint Motion constrained
A. Revolute 1. Three
B. Cylindrical 2. Five
C. Spherical 3. Four
Explanation: For revolute pair, degree of freedom = 1 and constrained
DOF = 6 – 1 = 5
For cylindrical pair, dof =2 and constrained dof = 6 – 2 = 4
For spherical pair, dof = 3 and constrained dof = 6 – 3 = 3.
6. The number of binary links, number of binary joints and number of ternary joints in Peaucelliar mechanism is
Explanation: The Peaucelliar mechanism has 8 binary links, 2 binary joints nad 4 ternary joints.
7. The number of degree of freedom of a planer linkage with 8 links and 9 simple revolute joints is
Explanation: L = 8 = number of links
P = 9 = number of simple revolute joints
F = 3(L – 1) – 2P
= 3(8 – 1) – 2 x 9
= 21 – 18
8. The following list of statements is given:
1) Grashoff’s rule states that for a planar crank-rocker 4-bar mechanism, the sum of the shortest and longest link lengths cannot be less than the sum of the remaining two link lengths.
2) Inversions of a mechanism are created by fixing different links, one at a time.
3) Geneva mechanism is an intermittent motion device.
4) Grubler’s criterion assumes mobility of a planar mechanism to be one.
The number of correct statements in the above list is
Explanation: Except statement 1, all other three statements are correct.
9. A mechanism has 8 links, out of which 5 are binary, 2 are ternary and 1 is quaternary. The number of instantaneous centres of rotation will be
Explanation: n = 5 + 4 + 3 = 12
Number of instantaneous centres, N = n(n – 1)/2
= 12 x (12 – 1)/2
10. In a dynamically equivalent system, a uniformly distributed mass is divided into
a) Three point masses
b) Four point masses
c) Two point masses
d) Infinite point masses
Explanation: Dynamically equivalent system of a rigid body is made of two point masses.
11. A crank and slotted lever mechanism used in a shaper has a centre distance of 300 mm between the centre of oscillation of the slotted lever and the centre of rotation of the crank. The radius of the crank is 120 mm. Find the ratio of the time of cutting to the time of return stroke.
Explanation: Given : AC = 300 mm ; CB = 120 mm
sin∠CAB = sin (90°−α/ 2)
CB/AC = 120/300 = 0.4
∠CAB = 90°−α/ 2
or α / 2 = 90° – 23.6° = 66.4°
α = 2 × 66.4 = 132.8°
We know that
Time of cutting stroke/ Time of return stroke = 1.72.
12. The magnitude of velocities of the points on a rigid link is directly proportional to the distances from the points to the instantaneous centre.
Explanation: The magnitude of velocities of the points on a rigid link is inversely proportional to the distances from the points to the instantaneous centre and is perpendicular to the line joining the point to the instantaneous centre.
13. The velocity of the instantaneous centre relative to any third rigid link will be different.
Explanation: The velocity of the instantaneous centre relative to any third rigid link will be same whether the instantaneous centre is regarded as a point on the first rigid link or on the second rigid link.
14. When the pin connects one sliding member and the other turning member, the angular velocity of the sliding member is __________
Explanation: When the pin connects one sliding member and the other turning member, the angular velocity of the sliding member is zero. In such cases,
Rubbing velocity at the pin joint = ω.r
where ω = Angular velocity of the turning member, and
r = Radius of the pin.
15. In a slider crank mechanism, the velocity of piston becomes maximum when
a) Crank and connecting rod are in line with each other
b) Crank is perpendicular to the line of stroke of the piston
c) Crank and connecting rod are mutually perpendicular
d) Crank is 1200 with the line of stroke
Sanfoundry Global Education & Learning Series – Machine Kinematics.
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