Physics key terms

The time during which a stopping force acts to bring an object to rest.

The amount of energy held in a particular energy store, such as a chemical, kinetic or thermal energy store.

A shape designed to allow a fluid to flow around an object more smoothly, reducing drag at a given speed.

Shaping an object so that it experiences less resistance as it moves through a fluid such as air.

A change of shape in which an object becomes longer because forces pull different parts apart.

A flashing light that can make a repeating wave pattern appear stationary when its flashing frequency is matched appropriately to the waves.

A particle smaller than an atom, such as a proton, neutron or electron.

The change from a solid directly to a gas, without passing through the liquid state.

A unit smaller than the unprefixed unit, formed using a multiplier less than one, such as a millimetre.

Equipment is suitable for a measurement if it can give a useful reading for the wave being investigated, with limitations that can be identified and evaluated.

An exploding star whose light can help astronomers investigate the expansion of the universe.

Using a renewable resource no faster than it can be replaced.

A transverse seismic wave that travels through solids but cannot travel through liquids.

A component that opens or closes a conducting path in a circuit.

An object or group of objects chosen for study, with a boundary separating it from the surroundings.

An error that shifts measurements consistently away from the true value by a similar amount or proportion.

The dividing line between a system and its surroundings; it determines what is included in the energy account.

A straight line drawn to touch a curve at a chosen point and match its slope there.

The velocity of an object at an instant, directed along the tangent to its circular path.

To set a balance to zero with an empty container on it, so it measures only what is added.

The practical use of scientific knowledge to meet a need or solve a problem.

An instrument that collects electromagnetic radiation from a distant object so it can be detected or imaged.

A measure related to the average kinetic energy of the molecules in a gas.

The difference between the final and initial temperatures: $\Delta\theta=\theta_{\text{final}}-\theta_{\text{initial}}$.

A material that becomes magnetised readily but loses most of its magnetism when the magnetising field is removed.

The pulling force exerted by a stretched rope, string or cable.

The constant velocity reached by an object moving through a fluid when the resistive force balances the driving force, so the resultant force and acceleration are zero.