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SHM · Lecture 1 of 26

What is SHM? Periodic, oscillatory and simple harmonic motion

By Lalit, IIT Madras

Periodic, oscillatory and simple harmonic motion told apart for JEE, with the force law F = −kx that makes a motion SHM.

Watch lecture 1

A chalkboard titled 'Four things, three kinds of motion' with a fan, a pendulum marked with its mean position and two extremes, a clock face and a spring-block on a floor, beside a line showing one oscillation as mean, extreme, mean, extreme, mean over a time T with half of it marked, and two nested circles for periodic and oscillatory motion.

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What this lecture covers

Four moving things in a room set up three kinds of motion. Periodic motion repeats after a time period T, the least such time. Oscillatory motion goes to and fro about a mean position, and with no friction its energy stays fixed. SHM can be linear or angular. With x measured from the mean position, a spring's restoring force is F = −kx, where k belongs to the system. Trying F = −kx^n shows why only n = 1 is SHM.

In this lecture

  1. Play from Why SHM matters: four moving things
  2. Play from Periodic motion and time period T
  3. Play from Oscillatory motion and mean position
  4. Play from No damping, and linear vs angular SHM
  5. Play from Displacement x and the restoring force
  6. Play from F = −kx and the spring constant k
  7. Play from Using F = −kx with a negative x
  8. Play from F = −k x^n: why only n = 1 is SHM
  9. Play from Three kinds of motion as sets
  10. Play from Recap: what SHM is