Ans :- If a number of bodies are assembled in such a way that the motion of one causes constrained and predictable motion to the others, it is known as a mechanism. A mechanism transmits and modifies a motion.
2.What is Machine ?
3.What is Rigid body ?
Ans :- A body is said to be rigid if under the action of forces, it does not suffer any distortion.
4.What is Resistant bodies ?
Ans :- Those which are rigid for the purposes they have to serve.
5.What is Semi rigid body ?
Ans :- Which are normally flexible, but under certain loading conditions act as rigid body for the limited purpose.
Example: 1. Belt is rigid when subjected to tensile forces. So belt-drive acts as a resistant body.
2. Fluid is resistant body at compressive load.
6.What is Kinematic pair ?
Ans :- A kinematic pair or simply a pair is a joint of two links having relative motion between them is know as Kinematic pair .
7.What is Derived Units ?
Ans :- Some units are expressed in terms of fundamental units known as derived units, e.g., the units
of area, velocity, acceleration, pressure, etc.
8.What is C.G.S. Units ?
Ans :- In this system, the fundamental units of length, mass and time are centimetre, gram and
second respectively. The C.G.S. units are known as absolute units or physicist's units.
9.What is F.P.S. Units ?
Ans :- In this system, the fundamental units of length, mass and time are foot, pound and second
respectively.
10.What is M.K.S. Units ?
Ans :- In this system, the fundamental units of length, mass and time are metre, kilogram and second
respectively. The M.K.S. units are known as gravitational units or engineer's units.
11.What is Metre ?
Ans :- The international metre may be defined as the shortest distance (at 0°C) between the two parallel lines, engraved upon the polished surface of a platinum-iridium bar, kept at the International
Bureau of Weights and Measures at Sevres near Paris.
12.What is Force ?
Ans :- It is an important factor in the field of Engineering science, which may be defined as an agent,
which produces or tends to produce, destroy or tends to destroy motion.
13.What is Kilogram ?
Ans :- The international kilogram may be defined as the mass of the platinum-iridium cylinder,
which is also kept at the International Bureau of Weights and Measures at Sevres near Paris.
14.What is Second ?
Ans :- The fundamental unit of time for all the three systems, is second, which is 1/24 × 60 × 60
= 1/86 400th of the mean solar day. A solar day may be defined as the interval of time, between the instants, at which the sun crosses a meridian on two consecutive days. This value varies slightly
throughout the year. The average of all the solar days, during one year, is called the mean solar day.
15.What is Plane Motion ?
Ans :- When the motion of a body is confined to only one plane, the motion is said to be plane motion. The plane motion may be either rectilinear or curvilinear.
16. What is Rectilinear Motion ?
Ans :- It is the simplest type of motion and is along a straight line path. Such a motion is also known as translatory motion.
17. What is Curvilinear Motion ?
Ans :- It is the motion along a curved path. Such a motion, when confined to one plane, is called plane curvilinear motion.
18.What is Mass ?
Ans :- It is the amount of matter contained in a given body, and does not vary with the change in its
position on the earth's surface. The mass of a body is measured by direct comparison with a standard mass by using a lever balance.
19.What is Weight ?
Ans :- It is the amount of pull, which the earth exerts upon a given body. Since the pull varies with distance of the body from the centre of the earth, therefore the weight of the body will vary with its position on the earth’s surface (say latitude and elevation). It is thus obvious, that the weight is a force.
20.What is Works ?
Ans :- Whenever a force acts on a body and the body undergoes a displacement in the direction of the
force, then work is said to be done.
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