What is a pendulum? Explain how a pendulum works.
http://en.wikipedia.org/wiki/Pendulum
http://nawcc.org/index.php/just-for-kids/about-time/how-does-it-work
A pendulum is a simple device consisting of a weight, called a bob, attached to a string or rod. It is primarily used to measure time, but it also has other applications in physics and engineering.
To understand how a pendulum works, let's break it down into its crucial components and the forces acting on them:
1. Length: The length of the string or rod affects the time it takes for the pendulum to swing back and forth, also known as its period. Longer pendulums have a longer period, while shorter pendulums have a shorter period.
2. Bob: The weight at the end of the pendulum is known as the bob. It can be any object with sufficient mass. The bob experiences the force of gravity pulling it downwards.
3. Restoring Force: When the bob is displaced from its equilibrium position (hanging straight down), a force called the restoring force begins to act on it. This force is proportional to the displacement and always acts towards the equilibrium position. In the case of a pendulum, the restoring force is provided by the tension in the string or the weight of the rod.
4. Gravity: Gravity is the force that pulls the bob downwards. It provides the energy needed for the pendulum to swing.
When a pendulum is set into motion, gravity pulls the bob downward, causing it to swing away from its equilibrium position. As it swings, the restoring force comes into play, pulling the bob back towards the equilibrium position. The bob's energy constantly interchanges between potential energy (at the highest point of the swing) and kinetic energy (at the lowest point of the swing).
The period of a pendulum, which is the time it takes to complete one full swing back and forth, can be calculated using the following formula:
T = 2π√(L/g)
Where:
T is the period of the pendulum,
L is the length of the string or rod, and
g is the acceleration due to gravity (approximately 9.8 m/s^2 on Earth).
Pendulums are often used in devices such as clocks because their period remains constant regardless of the amplitude (the distance the pendulum swings from its equilibrium position). This property is known as isochronism and makes pendulums a reliable means of measuring time.