Define following terms
(i) Kinematic link
(ii) Kinematic pair
(iii) Kinematic chain
(i) Kinematic link: Each part of a machine, which moves relative to some other part, is known as a
(ii) Kinematic pair: The two links or elements of a machine, when in contact with each other, are said to
form a pair. If the relative motion between them is completely or successfully constrained (i.e. in a
definite direction), the pair is known as kinematic pair.
(iii) Kinematic chain: 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
(iv) Mechanism: 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 e.g. engine indicators, typewriter etc.
(v) Machine: A machine is a device which receives energy and transforms it into some useful work.
(vi) Inversion: When one of links is fixed in a kinematic chain, it is called a mechanism. So we can obtain
as many mechanisms as the number of links in a kinematic chain by fixing, in turn, different links in a
kinematic chain. This method of obtaining different mechanisms by fixing different links in a kinematic
chain is known as inversion of the mechanism.