pendulum

(noun)

A body suspended from a fixed support so that it swings freely back and forth under the influence of gravity; it is commonly used to regulate various devices such as clocks.

Related Terms

Examples of pendulum in the following topics:

  • The Physical Pendulum

    • In contrast, a physical pendulum (sometimes called a compound pendulum) may be suspended by a rod that is not massless or, more generally, may be an arbitrarily-shaped, rigid body swinging by a pivot (see ).
    • In this case, the pendulum's period depends on its moment of inertia around the pivot point .
    • This is of the same form as the conventional simple pendulum and this gives a period of:
    • As with a simple pendulum, a physical pendulum can be used to measure g.
    • This is another example of a physical pendulum.

  • The Simple Pendulum

    • Example:Measuring Acceleration due to Gravity: The Period of a Pendulum.What is the acceleration due to gravity in a region where a simple pendulum having a length 75.000 cm has a period of 1.7357 sStrategy: We are asked to find g given the period T and the length L of a pendulum.
    • For small displacements, a pendulum is a simple harmonic oscillator.
    • For the simple pendulum:
    • or the period of a simple pendulum.
    • Even simple pendulum clocks can be finely adjusted and accurate.

  • Energy Transformations

    • For example, imagine a pendulum in a vacuum.
    • However, when the pendulum is at its lowest point, all of its energy exists in the form of kinetic energy.
    • This animation shows the velocity and acceleration vectors for a pendulum.
    • One may note that at the maximum height of the pendulum's mass, the velocity is zero.
    • This corresponds to zero kinetic energy and thus all of the energy of the pendulum is in the form of potential energy.

  • Second-Order Linear Equations

    • A simple pendulum, under the conditions of no damping and small amplitude, is described by a equation of motion which is a second-order linear differential equation.

  • Introduction to Simple Harmonic Motion

    • For instance, the motion of a plane pendulum of length $\ell$ (Figure 1.1) is governed by
    • So for small displacements, the equation for the pendulum is:
    • Thus the equation of motion for the pendulum is linear in $\theta$ when $\theta$ is small.

  • Projecting Vectors Onto Other Vectors

    • We did this, in effect, when we computed the tangential force of gravity on a simple pendulum.

  • Time

    • For example, the movement of the sun across the sky, the phases of the moon, the swing of a pendulum, and the beat of a heart have all been used as a standard for time keeping.

  • Energy in a Simple Harmonic Oscillator

    • For example, for a simple pendulum we replace the velocity with v=Lω, the spring constant with k=mg/L, and the displacement term with x=Lθ.
    • A similar calculation for the simple pendulum produces a similar result, namely:

  • Back EMF, Eddy Currents, and Magnetic Damping

    • Consider the apparatus shown in , which swings a pendulum bob between the poles of a strong magnet.
    • (a) The motion of a metal pendulum bob swinging between the poles of a magnet is quickly damped by the action of eddy currents.

  • Laissez-Faire Versus Government Intervention

    • American history has seen the pendulum swing repeatedly between laissez-faire principles and demands for government regulation of both types.