Question

Oscillatory motion among the following is
a. Rotation of the earth about its axis
b. Revolution of the moon about the earth
c. To and fro movement of a vibrating string
d. All of these

Answer 1

To and fro movement of a vibrating string is in an oscillatory motion. It is that type of motion which repeats itself time and again in to and fro movement reaching a state of equilibrium in between.

If there were no friction the motion would have continued forever and would never be in a state of rest.

Oscillatory motion can be found in many objects from the nucleus to clock pendulum.  

Answer 2

Answer:

I think it's To and fro movement of a vibrating string