How close our experimental measurements are to the true value.
Dependent Variable
The result or effect we’re looking at in an experiment – we change the independent variable in an experiment, and that causes the dependent variable to change.
Electricity
The flow of electrons around a circuit, from one end of the battery (or power supply) to the other.
Energy
The ability to do work, or alternatively, the currency with which all work in the universe is done.
Fluid
Substances (gases and liquids) that flow freely.
Force
A push or a pull on an object.
Independent Variable
The thing we change in an experiment to see what the result will be – we change the independent variable in an experiment, and that causes the dependent variable to change.
Line Of Best Fit
A line drawn between data points on a scatter graph, which best represents that data. A line of best fit can be straight or curved.
Instrument Error
The uncertainty or range in possible values of a measurement, based on the limitations of the device/instrument.
Momentum
The product of the mass and the velocity. Things with greater mass have more momentum, and things gain momentum when they get faster.
Motion
The movement (or change in position) of an object relative to a point of reference (usually the Earth’s surface).
Optics
The study of the behavior of light, including human sight.
Precision
The number of digits used when taking a reading. For example, we can say that Anchorage, Alaska and Los Angeles, California are 5000 km apart, 5500 km apart, 5470 km apart, 5472 km apart, 5472.6 km apart or 5472.57 km apart. All these answers are correct. The difference between them is the precision they were measured to. Notice that if you measure too precicely, you will probably be inaccurate. Measuring the distance between cities down to the centimeter is silly as we don't have a definite line for where the cities begin and end.
Random Error
Variation in experimental measurements due to natural random fluctuations: like the variations in stopwatch measurements, for example.
SI Units
The standard, international system of units used by all physicists and almost all scientists. The seven basic SI units are meters, kilograms, seconds, amperes, kelvin, moles, and candelas. All other units (like newtons and joules) are really combinations of those seven.
Systematic Error
Where all of our measurements are off by a consistent amount (2 cm too large, 3 cm too small etc.) This is usually caused by miscalibrated instruments, or measuring from the wrong place.
Thermodynamics
The study of the movement of heat.
Wave
A vibration in space and time which carries energy. Examples include sound waves, light waves, and water waves.