Glossary
Search every term used across the theory and the labs.
- Energy
- The capacity to do work. Measured in joules (J).
- Work
- Work is done when a force moves its point of application: W = F × s × cos θ.
- Kinetic energy
- The energy possessed by a body due to its motion, K = ½mv².
- Potential energy
- The energy possessed by a body due to its position or configuration; gravitational PE is U = mgh.
- Mechanical energy
- The sum of the kinetic and potential energies of a body, E = K + U.
- Principle of conservation of energy
- Energy can neither be created nor destroyed; it only changes from one form to another, so the total energy of the universe remains constant.
- Conservative force
- A force such as gravity for which the work done does not depend on the path taken; mechanical energy is conserved.
- Dissipative force
- A force such as friction or air resistance that converts mechanical energy into heat.
- Free fall
- Motion of a body under gravity alone, with no air resistance.
- Acceleration due to gravity (g)
- 9.8 m/s² on Earth, 1.62 m/s² on the Moon and 3.71 m/s² on Mars.
- Simple pendulum
- A small heavy bob suspended by a light inextensible string from a rigid support.
- Mean position
- The lowest point B of a pendulum's swing, where speed and kinetic energy are maximum.
- Extreme position
- The highest points A and C of a swing, where the bob is momentarily at rest and PE is maximum.
- Amplitude
- The maximum displacement of the bob from the mean position.
- Time period
- The time taken for one complete oscillation, T = 2π√(L/g) for small angles.
- Joule
- The SI unit of energy: the work done when a force of 1 N moves a body through 1 m.
- Heat energy
- Energy transferred because of a temperature difference; the usual destination of energy lost to friction.
- Energy transformation
- The change of energy from one form into another, such as potential energy into kinetic energy.