Engineering Questions with Answers - Multiple Choice Questions

# Machine Kinematics – Simple Mechanisms – 1

1 - Question

In a reciprocating steam engine, which of the following forms a kinematic link ?
a) cylinder and piston
b) piston rod and connecting rod
c) crank shaft and flywheel
d) flywheel and engine frame
View Answer Answer: c
Explanation: in a reciprocating steam engine, piston, piston rod and crosshead constitute one link ; connecting rod with big and small end bearings constitute a second link ; crank, crank shaft and flywheel a third link and the cylinder, engine frame and main bearings a fourth link.

2 - Question

The motion of a piston in the cylinder of a steam engine is an example of
a) completely constrained motion
b) incompletely constrained motion
c) successfully constrained motion
d) none of the mentioned
View Answer Answer: a
Explanation: The piston and cylinder in a steam engine form a pair and the motion of the piston is limited to a definite direction (i.e. it will only reciprocate) relative to the cylinder irrespective of the direction of motion of the crank.

3 - Question

The motion transmitted between the teeth of gears in mesh is
a) sliding
b) rolling
c) may be rolling or sliding depending upon the shape of teeth
d) partly sliding and partly rolling
View Answer Answer: d
Explanation: 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, and in mesh the gears have a point contact.

4 - Question

The cam and follower without a spring forms a
a) lower pair
b) higher pair
c) self closed pair
d) force closed pair
View Answer Answer: c
Explanation: When the two elements of a pair are connected together mechanically in such a way that only required kind of relative motion occurs, it is then known as self closed pair. The lower pairs are self closed pair and the motion of cam and follower is relative to each other.

5 - Question

A ball and a socket joint forms a
a) turning pair
b) rolling pair
c) sliding pair
d) spherical pair
View Answer Answer: d
Explanation: When the two elements of a pair are connected in such a way that one element (with spherical shape) turns or swivels about the other fixed element, the pair formed is called a spherical pair, and ball and socket joint are such pairs.

6 - Question

The lead screw of a lathe with nut forms a
a) sliding pair
b) rolling pair
c) screw pair
d) turning pair
View Answer Answer: c
Explanation: When the two elements of a pair are connected in such a way that one element can turn about the other by screw threads, the pair is known as screw pair. The lead screw of a lathe with nut, and bolt with a nut are examples of a screw pair.

7 - Question

When the elements of the pair are kept in contact by the action of external forces, the pair is said to be a
a) lower pair
b) higher pair
c) self closed pair
d) force closed pair
View Answer Answer: d
Explanation: When the two elements of a pair are not connected mechanically but are kept in contact by the action of external forces, the pair is said to be a force-closed pair. The cam and follower is an example of force closed pair, as it is kept in contact by the forces exerted by spring and gravity.

8 - Question

Which of the following is a turning pair ?
a) Piston and cylinder of a reciprocating steam engine
b) Shaft with collars at both ends fitted in a circular hole
c) Lead screw of a lathe with nut
d) Ball and socket joint
View Answer Answer: b
Explanation: When the two elements of a pair are connected in such a way that one can only turn or revolve about a fixed axis of another link, the pair is known as turning pair. A shaft with collars at both ends fitted into a circular hole, the crankshaft in a journal bearing in an engine, lathe spindle supported in head stock, cycle wheels turning over their axles etc. are the examples of a turning pair.

9 - Question

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
View Answer Answer: c
Explanation: When the kinematic pairs are coupled in such a way that the last link is joined to the first link to transmit definite motion (i.e. completely or successfully constrained motion), it is called a kinematic chain. In other words, a kinematic chain may be 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.

10 - Question

The relation between the 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
View Answer Answer: c
Explanation: If each link is assumed to form two pairs with two 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 = 2 p – 4