# NCERT Class 11 Physics Solutions: Chapter 14 – Oscillations-Part 7 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 14.11**:

Figures correspond to two circular motions. The radius of the circle, the period of revolution, the initial position, and the sense of revolution (i.e.. clockwise or anti-clockwise) are indicated on each figure.

Obtain the corresponding simple harmonic motions of the x-projection of the radius vector of the revolving particle in each case.

**Answer**:

**For Figure**

Time period,

Amplitude,

At time, , the radius vector makes an angle with the positive , i.e.. ,

Phase angle

Therefore, the equation of simple harmonic motion for the projection of , at time , is given by the displacement equation:

**For Figure**

Time period,

Amplitude,

At time , makes an angle with the x-axis, in the anticlockwise direction.

Hence, phase angle,

Therefore, the equation of simple harmonic motion for the projection of at time is given as: