Depending on the shape of the pendulum, a pendulum can be categorized as a
simple one (simple pendulum) or a compound one (physical pendulum). A simple
pendulum is a mass hung vertically by a string from a fixed point in a way that it can
swing freely. In a physical pendulum a rigid body is suspended from a fixed point in a
way that it can move freely about its position of equilibrium.
When a simple pendulum is in motion (swinging) it keeps a very regular and
consistent beat, and for this manner it has been used for different purposes such as,
laboratories and scientific apparatus, clocks, astronomical measurements, and etc.
While constructing labs as such it is important that the observer records not one but
five or even ten periods and calculate an average. By doing this accuracy goes up,
and a lower percentage error would be received.
When describing a pendulum’s motion, one of the factors to consider would
be its period (T), which can be affected by the mass of the bob, length of the swing,
and the amplitude of the pendulum.
However, current studies and theories show
that the period of the pendulum depends only on the length of its swing.
When a pendulum is in motion as shown in figure (1), its mass (the bob of the
pendulum) moves in a simple harmonic motion, where the inertia is the bob.
Whenever the mass passes through the midpoint the direction of the tangential
component will change and therefore restoring the mass to the central position
restoring force can be calculated from the following equation: