Question

What is common to the following?
the propeller of a flying helicopter; the second hand of a watch; the tape of a cassette recorder
(a) examples of translatory motion
(b) examples of oscillatory motion
(c) examples of rotatory motion
(d) examples of periodic motion

Answer 1

(a) examples of rotatory motion

When every point on a moving body moves around a fixed centre or an axis of rotation, the motion is called rotatory motion. The propeller of a flying helicopter, the second hand of a watch and the tape of a cassette recorder moves around a fixed centre. Hence, these are examples of rotatory motion.