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Simple Pendulum

A simple pendulum (see Figure 1) is a simplified version of a 'real' pendulum where the following simplifications are assumed:

  • The thread has no mass and cannot extend

  • The mass attached to the thread is a point mass

  • The motion is two-dimensional

  • There is no friction or air resistance

An image of a small weight of a mass m, suspended on a thread of the length ‘L’. The weight is inclined from the vertical axis by the angle theta. The forces acting are marked as arrows. Blue arrow starts in the middle of the weight and points towards the vertical axis, and is described as ‘m’ times ‘g’ times sine of theta. Red arrow starts in the middle of the weight and points downwards, and is described as m times ‘g’. Black arrow points downwards at the angle of theta, and it is described as ‘m’ times ‘g’ times cosine of theta.

Figure 1: A simple pendulum with thread length L, mass m, angular displacement θ

Here you can find the theory for derivation of oscillation period and gravitational acceleration.

Referred from:

Article
Derivation of oscillation period and gravitational acceleration