INTRODUCTION

We have already discussed in chapter 23 the simple harmonic motion of bodies without any reference to the force causing such a motion. But in this chapter, we shall discuss the forces causing simple harmonic motion of the following bodies :

1. Helical springs,

2. Simple pendulum,

3. Compound pendulum, and

4. Conical pendulum.

HELICAL SPRINGS

Consider a closely-coiled helical springs whose upper end is fixed as shown in Fig 26.1.

HELICAL SPRINGS IN SERIES AND PARALLEL

SIMPLE PENDULUM

A simple pendulum, in its simplest form, consists of a heavy bob suspended at the end of a light inextensible, flexible string and the other end of the string is fixed at O as shown in Fig 26.4.

LAWS OF SIMPLE PENDULUM