Correct Answer - Option 2 : Q

__Concept:__

**Simple harmonic motion: **

- It is a
**special type of periodic motion**, in which a **particle moves to and fro **repeatedly about a mean position.
- In linear S.H.M. a
** restoring force** which is always directed towards the mean position and whose magnitude at any instant is **directly proportional to the displacement** of the particle from the mean position at that instant

Restoring force ∝ Displacement of the particle from mean position.

F = -kx

Where k is known as force constant. It's S.I. unit is Newton/meter

The general expression for the wave is given by:

**y = A Sin (ωt + θ)**

**y = 0 is the mean position of particle**

Where A = amplitude of wave, ω = angular frequency, t is time and θ = phase angle,

**Amplitude: **It is the maximum displacement of the object from the equilibrium position.

__Calculation:__

Motion of particle is given by

y = P + Q sin ωt

⇒ y - P = Q sin ωt

So, particles execute SHM with mean position y = P.

Let y -P = y'

⇒ y' = Q sin ωt

Comparing this equation by equation of SHM,

We will get amplitude

A = Q

Hence, particles execute simple harmonic motion with **amplitude Q.**