### CHAPTER NO 10 SIMPLE HARMONIC MOTION & WAVES

Simple Harmonic Motion.

Class: 10th Class Physic Notes

Subject: Physics

Chapter: Simple harmonic motion and waves

Topic: Simple harmonic motion

Class: 10th Class Physic Notes

Subject: Physics

Chapter: Simple harmonic motion and waves

Topic: Simple harmonic motion

#### Major Concepts

- SHM, necessary conditions, and examples
- Damped oscillation
- Wave motion
- Types of waves and their examples
- Waves equations
- Ripple Tank
- Characteristics of Waves
- Solution of problems

**Q:1 What is Periodic motion? Give examples.**

**Ans. Periodic Motion:**

**Definition:**

“The motion which repeats itself after regular intervals of time is called periodic motion.”

**Examples:**

- The motion of the bob of the pendulum f.s.
- The motion of the mass attached to spring.
- Oscillations of the steel strip.
- The motion of the earth around its axis.

**Q 2. Define the following terms?**

__Ans.Definition of terms:__

**a) Vibration (or) Oscillation:**

“One complete round tip of a vibrating body is called vibration”.

**b) Time Period:**

The time required for the completion of one round trip is called time period.”

**c) Frequency:**

The number of vibrations completed by a vibrating body in one second is called frequency.”

**d) Displacement:**

“The distance covered by a vibrating body on either side of the mean position is called displacement. It is denoted by ‘x’.”

**e) Amplitude:**

“The maximum displacement covered by a vibrating body on either side of the mean position is called amplitude. It is denoted by’ x0‘.”

**Q3: Define simple harmonic motion (S.H.M) with examples. Describe its characteristics?**

**Ans. Simple Harmonic motion:**

“The type of periodic motion in which acceleration is directly proportional to the displacement from the mean position and always directed toward the mean position is called simple harmonic motion (S.H.M).

**Examples:**- The motion of the bob of the simple pendulum.
- The motion of a mass attached to spring.

__Characteristics:__- The characteristics of simple harmonic motion are as follows.
- In S.H.M, the body oscillates about its mean position.
- In S.H.M, the acceleration of the body is directly proportional to the displacement from the mean position and directed toward the mean position& directed toward the mean position i.e.

- In S.H.M restoring force is always acting upon the body.
- The restoring force and acceleration are Maximum at the extreme position and zero at the mean position.
- The velocity and K.E are maximum at the mean position and zero at the extreme position.
- Potential energy is maximum at an extreme position and zeroes at the mean position.

**Q4: Show that the motion of a mass attached with spring execute S.H.M. Describe its characteristics?**

__Ans. Definition:__“The type of periodic motion in which acceleration is directly proportional to displacement form the mean position and always directed toward the mean position is called simple harmonic motion (S.H.M).

__Mathematically:__

__Proof:__To show that the motion of a mass attached with spring is S.H.M, let us consider mass “m” is attached to one end of the spring as shown in the figure.

**Q.5.What is a simple pendulum?**

__Ans. Simple pendulum:__“An ideal pendulum consists of a small heavy bob of mass ‘m’ suspended by a light string of length ‘L’ fixed with frictionless support.”

__The motion of a simple pendulum is SHM:__Consider an object of mass ‘m’ attached with one end of a light string of length ‘L’ as shown in Fig.

__Length of the pendulum:__The length of the pendulum ‘L’ is the distance between the point of suspension

and the center of the Bob, when the

the pendulum is at Equilibrium position ‘O’, the net force on the bob is zero and the bob is stationary.

Now if we bring the bob to extreme position A, the net force is not zero as shown in fig.