Study Guide

Physics Basics Terms

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Physics Basics Terms


The degree to which a measurement is close to an actual, exact value.

Dependent variable

This is the variable that depends on how the independent variable is feeling at the moment. It's a tough job, but someone's got to do it.


The flow of electrons around a circuit, from one end of the battery (or power supply) to the other.


The ability of an object to do work. Energy comes in many different forms—mechanical, chemical, thermal, and more—and cannot be created nor destroyed, only changed in form. The base SI unit is a joule, where . The unit is named after James Prescott Joule, who discovered the link between heat and mechanical energy. A joule is a very small unit—1 Calorie of food energy is equivalent to over 4000 J.


Substances (gases and liquids) that flow freely.


We think of a force as a great influence in our lives. Forces decide what happens to what, where, when, and how and does it all from various distances including but not limited to gravity, friction, and magnetism. Force is an influential friend with telekinesis powers.

Independent Variable

Variable in a function that assumes a value freely or independently.

Line Of Best Fit

This is the line that best describes a set of bivariate data points.

Instrument error

The uncertainty or range in possible values of a measurement, based on the limitations of the device/instrument.


The product of an object's mass and velocity, abbreviated "p'' because physics always makes sense, that's why. The formula to remember is p = mv; this means momentum is in units of kilogram-meters-per-second, or, equivalently, newton-seconds. No scientist's name has been given to this unit yet, but if you write us a check we might be willing to talk to the right people for you. You know, to get the ball rolling and really give the idea some momentum.


The movement (or change in position) of an object relative to a point of reference (usually the Earth’s surface).


The study of the behavior of light, including human sight.


The degree to which a bunch of measurements are close to one another.

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.


The study of the movement of heat.


A wave is an oscillation. But more than that, a wave is a repeated set of oscillations—repeated motion away from and back to an equilibrium point. Many kinds of "repetitive motion" can be described as waves, from things we traditionally call waves (light or sound or the motion of the ocean) to back-and-forth motion of physical objects (swing sets or see-saws or clock pendulums). Mechanical waves travel through a medium: sound is a wave of air molecules jostling back and forth, and earthquakes are oscillations in the rock of earth's crust. Electromagnetic waves don't need a medium to travel through—we send radio waves to space to communicate to satellites. "The Wave" travels through a very specific medium: sports stadiums full of people.

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