Simple pendulum

Definition

A simple pendulum consists of a mass (called the bob) attached to the end of a lightweight string or rod that swings freely under the influence of gravity. The motion is periodic and can be described by harmonic motion for small angles.

5 Must Know Facts For Your Next Test

1. The period of a simple pendulum is given by $T = 2\pi \sqrt{\frac{L}{g}}$, where $L$ is the length of the pendulum and $g$ is the acceleration due to gravity.
2. For small angular displacements (less than approximately 15 degrees), the motion of a simple pendulum approximates simple harmonic motion.
3. The restoring force in a simple pendulum is provided by gravity and acts along the arc of the pendulum's swing.
4. The period of a simple pendulum is independent of its mass and amplitude, assuming small oscillations.
5. Energy in a simple pendulum system oscillates between kinetic energy and gravitational potential energy.

Review Questions

• What factors affect the period of a simple pendulum?
• Why does a simple pendulum exhibit harmonic motion only for small angles?
• How does gravitational potential energy change as a pendulum swings?

Related terms

Period:

The time taken for one complete cycle of oscillation. For a simple pendulum, it depends on the length of the string and gravity.

Restoring Force:

A force that gives rise to an equilibrium in a physical system. In a simple pendulum, this force is due to gravity.

Simple Harmonic Motion:

A type of periodic motion where the restoring force is directly proportional to displacement and acts in the direction opposite to that displacement.