Question

how can we define shm?

Answer 1

The simplest kind of periodic motion (to and fro or back and forth) about a mean position under the influence of a restoring force which is directly proportional to the displacement from the mean position is called a Simple Harmonic Motion (SHM).

Following are the characteristics of SHM:

1. It is the simplest form of periodic motion.
2. It can be represented as a uniform circular motion.
3. At any instant of its motion, acceleration is directly proportional to the displacement.
4. The acceleration is always directed towards the mean position.
5. Potential energy is the maximum at the maximum displacement and kinetic energy is the maximum at the mean position.