Distance is actually defined as length or space between two places. It is clear from the diagram that when we whirl the stone, the space or length between points A and B, i.e. between hand and stone does not change.
Hence, distance is same.

First of all, take a round pencil and try to wrap the given wire round the pencil making.
25 turns forming a coil. Now, measure the length of the wire that turns formed coil. Divide the total length of the coil by number of turns. This is the thickness of the Wire.

The earth performs two types of motion. One of the motions is when it moves around the sun, then it is said to possess circular motion and on the other hand, it also rotates about its own axis called rotational motion.

Two examples of periodic motions are
(i) Motion of the earth around the sun
(ii) To and fro movement of bob of a pendulum

Given, height of a person = 1.65 m
We know that
1 metre (m)= 100 centimetre (cm)
1 metre (m) = 1000 millimetre (mm)
(a) The height of a person in cm = 1.65x 100 cm = 165 cm
(b) The height of a person in mm = 1.65x 1000 mm = 1650 mm

By measuring distance by a particular standard unit of measurement, we can measure how far they have travelled.

Rotational and rectilinear motion are performed during the rolling of a ball.

Periodic motion is exhibited by the simple pendulum.

The device which is used to measure girth of a tree is a measuring tape.

The two contributions in 20th century towards transportation is electric trains and supersonic aeroplanes.

(a) Rectilinear motion The handle of bicycle will always move in rectilinear path because it cannot do circular or rotatory motion.
(b) Circular motion The Paddles of bicycle will always move circularly around its chain fixing system because it cannot move in forward direction without the whole chain system.
(c) Both rectilinear and circular The wheels of bicycle will move in rectilinear as well as in circular motion because the wheel as a whole will move forward and its point or particles around the rim will execute circular motion.

The motions of a wheel of a moving bicycle and a mark on the blade of a moving electric fan are different in the following ways.