# NCERT Class 11 Physics Solutions: Chapter 14 – Oscillations-Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 14.3**:

Figure depicts four plots for linear motion of a particle. Which of the plots represent periodic motion? What is the period of motion (in case of periodic motion) ?

**Answer**:

Are periodic

**Explanation**:

It is not a periodic motion. This represents a unidirectional, linear uniform motion. There is no repetition of motion in this case.

In this case, the motion of the particle repeats itself after Hence, it is a periodic motion, having a period of

It is not a periodic motion. This is because the particle repeats the motion in one position only. For a periodic motion, the entire motion of the particle must be repeated in equal intervals of time.

In this case, the motion of the particle repeats itself after . Hence, it is a periodic motion, having a period of

**Question 14.4**:

Which of the following functions of time represent,

(a) Simple harmonic,

(b) Periodic but not simple harmonic, and

(c) Non-periodic motion?

Give period for each case of periodic motion ( is any positive constant) :

**Answer**:

: Simple harmonic motion

**Explanation**:

The given function is:

This function represents SHM as it can be written in the form:

Its period is:

:

Periodic, but not Simple harmonic motion

**Explanation**:

The given function is:

The terms individually represent simple harmonic motion.

However, the superposition of two simple harmonic motion is periodic and not simple harmonic.

:

Simple harmonic motion.

**Explanation**:

The given function is:

This function represents simple harmonic motion because it can be written in the form:

Its period is:

: Periodic, but not simple harmonic motion

**Explanation**:

The given function is . Each individual cosine function represents simple harmonic motion. However, the superposition of three simple harmonic motions is periodic, but not simple harmonic.

: Non-periodic motion

**Explanation**:

The given function is an exponential function. Exponential functions do not repeat themselves. Therefore, it is a non-periodic motion.

:

The given function is non-periodic.