How does an object supposed to be at rest and in motion are considered to be relative ?

When is a body said to be in rest and motion ?

show that 'Rest' and 'Motion' are relative term.

The work done on an object does not depend upon the

An object may be regarded to be rest or in motion depending on the frame of reference chosen to view the object. Because of length contraction it would mean that the same rod may have two dfferent lenghts depending on the state of the observe. Is this true ?

If an object executes a to and fro motion about a fixed point, is an example for