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Motion, Forces, and Energy Energy and Tools Heat Light Sound


the distance traveled in a certain amount of time


any push or pull that makes an object start moving, stop moving, speed up, slow down, or change direction


a force between surfaces that slows objects down or stops them from moving


the tendency of an object to remain in motion or stay at rest unless acted upon by an outside force


the use of a force to move an object a certain distance


the ability to do work, either to make an object move or to change matter

simple machines

a machine with few moving parts, making it easier to do work; the six types of simple machines are the lever, pulley, wheel an axle, inclined plane, wedge, and screw


the object being lifted or moved by a machine

effort force

the amount of force needed to move something


the measure of how much useful work a machine puts out compared to the amount of work put into it


the movement of thermal energy from warmer to cooler objects


the transfer of energy between two objects that are touching


the transfer of energy by the flow of liquids or gases, such as water boiling in a pot or warm air rising in a room


the transfer of energy through space

fossil fuels

a substance such as coal or oil that was formed millions of years ago from the remains of plants and animals; these fuels are nonrenewable resources, and, when burned for energy, are a major source of pollution


the distance from the top of one wave to the top of the next


a range of light waves with different wavelengths


the bouncing of light waves off a surface


the bending of light as it passes from one transparent material into another


the back-and-forth motion of an object

sound wave

an area of bunched-up and spread-out air particles that moves outward in all directions from a vibrating object


the number of times a sound source vibrates in one second


the highness or lowness of a sound as determined by its frequency


the energy in a sound wave

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