Question

“A bird flapping its wings around a clock tower”. Which part of the motion is periodic and oscillatory?
A. Bird’s motion is oscillatory while flapping is periodic
B. Both bird’s motion and wing flapping were oscillatory
C. Bird’s motion is periodic while wing flapping is oscillatory
D. Both birds’ motion and wing flapping are non- oscillatory

Answer 1

Hint : Firstly we will explain the meaning of oscillatory and periodic motion so that we get an idea about them and then evaluate the motion and justify why one point is right while others are wrong in the given options. Taking the bird flying around the clock tower as circular motion and flapping of wings as motion too.

Complete step-by-step solution:
Explaining the terms: oscillatory motion and periodic motion.
Periodic motion: a motion that recursion (repeats itself) after a regular interval of time.
Oscillatory motion: a motion which a body moving in a back and forth motion in repeated manner in a mean point.
Since the clock tower is a fixed point around which the bird flies in a circular motion acts as a juncture for the periodic moment. With a fixed point the bird repeats its motion in an equal interval of time. Thus it is periodic. However, bird flapping is in the form of transverse wave with a tool and fro motion in a forward movement of its body; hence it’s an oscillatory
Reasons why other answers are wrong: -
(A) Bird motion around the clock tower can’t be oscillatory because there is no wave structure in its motion. Bird flies in circular path around the tower with no back and forth or too and fro motion, thus its motion around the tower is not oscillatory. Similarly, flapping cannot be periodic because motion of its wing is not in the fixed point. The bird changes its course every second thus creating a transverse wave of the motion, however, periodic motion is around a fixed point in a fixed interval of time for example-vibration of tuning fork.
(B) Bird motion can’t be oscillatory because its motion is not in the waveform but a bird flapping is in the waveform as it flies around the tower
(D) Wing flapping is in the form of wave thus it’s oscillatory
So Correct Option is (C) Bird’s motion is periodic while flapping is oscillatory.

Note: Oscillatory motion can be termed as harmonic motion or vibratory motion. Number of examples of oscillatory motion: weights on springs, pendulums, LC circuits, etc. Periodic motion examples are: The motion of the hands of a clock. Motion of a pendulum; Motion of a swing; Motion of Earth round the Sun.