Loading…
Loading…
Browse key terms and definitions across all GCSE subjects. Search by keyword or filter by subject and exam board.
23,110 key terms
Rate of change
A measure of how much a quantity changes over a specified interval, or the frequency of an event in a stated population during a stated period. Its units explain which meaning applies.
Rate of change of momentum
The change in momentum divided by the time taken. This is equal to the resultant force acting on the object.
Rate of change of speed
The change in speed per unit time; a positive change is acceleration and a decrease in speed is deceleration.
Rate of cooling
The decrease in temperature per unit time; it can be used to compare how quickly samples cool.
Rate of cooling
How quickly the temperature of a system decreases.
Rate of decay
The amount of biological material broken down per unit of time, often estimated from the mass lost by a sample.
Rate of diffusion
The amount of a substance crossing an exchange surface in a given time.
Rate of improvement
How much a performance measure improves over a given interval, such as each week or training session.
Rate of landform change
The speed at which the shape or position of a landscape feature changes, measured over a stated period.
Rate of oxygen uptake
The volume of oxygen taken up by living organisms per unit time, used here as a measure of their rate of aerobic respiration.
Rate of pay
Money earned per unit of work, such as pounds per hour.
Rate of photosynthesis
The amount of change measured per unit of time; here, oxygen bubbles produced per minute can estimate how quickly photosynthesis is occurring.
Rate of photosynthesis
The amount of photosynthesis occurring per unit time, estimated experimentally by oxygen production per unit time.
Rate of reaction
A measure of how much change occurs in a given time.
Rate of reaction
How quickly a reactant is used or a product is formed, expressed as a change in quantity per unit time.
Rate of reaction
The amount of reactant used up or product formed per unit time.
Rate of respiration
The volume of carbon dioxide produced by yeast per unit of time, used here as a measure of its rate of respiration.
Rate of thermal energy transfer
The amount of thermal energy transferred each second from a warmer object or place to a cooler one.
Rate of transpiration
The amount of water lost by a plant per unit time, often estimated by measuring its water uptake.
Rate of urbanisation
How quickly the proportion of a population living in urban areas changes over time.
Rate of water uptake
The amount of water taken into a plant or plant tissue in a given time.
Ratification
Formal approval of a proposed constitutional amendment. The ERA required approval by at least 38 states.
Ratification
The formal process through which a state agrees to be bound by a treaty.
Rating
A specified operating limit that a component must not exceed, such as a resistor’s maximum power dissipation.
Rating scale
A type of closed question in which participants select a position on a numerical or descriptive scale to indicate intensity, frequency or agreement.
Rating test
A test in which a score is assigned using a defined scale, for example to show liking for a sensory property.
Ratio
A comparison of quantities expressed in a specified order, such as .
Ratio
A comparison of two quantities, such as the estimated area of the cytoplasm compared with that of the nucleus.
Ratio
A comparison showing the relative amounts of two or more quantities. In a balanced chemical equation, the coefficients give the ratio of amounts in moles.
Ratio
A comparison between quantities written in a stated order, such as remaining : original.
Create a free account to keep every note you open and track your progress.