Yes, air around us is always transparent because we can see the objects through air clearly.

The two examples of a periodic motion are motion of a pendulum and motion of a child on a swing.

1m = 100em = 1000 mm
\(\therefore\)The height of the given person in cm is
= 1.965 x 100 = 196.5 cm
\(\therefore\)The height of the given person in mm is
= 1.965 x 1000 = 1.965 mm.

The two devices that are used to measure length are:
(i) Metre-scale (ii) Screw gauge.

An object is said to be at rest when it does not change its position with time. While an object is said to be in motion when it changes its position with time.

By marking 1/2, 1/4and 1/8 of string length

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

A body always rotates in its orbit in the case of circular motion while in the case of rotational motion, a body rotates about its axis.

Periodic motion is exhibited by the simple pendulum.

In ancient times, there were some modes of transportation like bullock cart, horse cart, camel cart, etc.

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

There are\(1\over 1000\) kilometre in 1 metre

The motion exhibited by a freely falling stone is rectilinear motion

Due to the changing position of hour hand of a wall clock, it always be in motion.

Rectilinear motion is the motion possessed by the vehicles on a straight road.