Term Definition
Reference point the starting point you choose to describe the location, or position, of an object
position an object distance and direction from a reference point
motion movement; process of changing position relative to a reference point.
displacement the difference between the initial position and the final position of an object
speed the distance an object moves divided by the time it takes to move that distance
constant speed the rate of change of position in which the same distance is traveled each second
Instantaneous spped an object's speed at a specific instant in time
average speed the total distance traveled divided by the total time taken to travel that distance
velocity the speed and the direction of a moving object
acceleration a measure of the change in velocity during a period of time
contact force a push or a pull on one object by another object that is touching it
force a push or a pull on an object
noncontact force a force that one object applies to another object without touching it
gravity an attractive force that exists between all objects that have mass
mass the amount of matter in an object
weight the gravitational force exerted on an object
fiction a contact force that resists the sliding motion of two surfaces that are touching
net force the combination of all the forces acting on an object.
balanced forces forces acting on an object that combine and form a net force of zero
unbalanced forces forces acting on an object that combine and form a net force that is not zero
newton's first law of motion law that states that if the net force acting on an object is zero, the motion of the object does not change
inertia the tendency of an object to resist a change in motion
newton's second aw of motion law that states that the acceleration of an object is equal to the net force exerted on the object divided by the object's mass
circular motion any motion in which an object is moving along a curved path.
centripetal force in circular motion, a force that acts perpendicular to the direction of motion, toward the center of the curve.
newton's third law of motion law that states that for every action there is an equal and opposite reaction
force pair the forces two objects apply to each other
momentum a measure of how hard it is to stop a moving object.
energy transformation the conversion of one form of energy to another
law of conservation of energy law that states that energy can be transformed from one form to another, but it cannot be created or destroyed
work the amount of energy used as a force moves an object over a distance
simple machine a machine that does work using one movement
inclined plane a simple machine that consists of a ramp, or a flat, sloped surface
screw a simple machine that consists of an inclined plane wrapped around a cylinder
wedge an inclined plan that moves
lever a simple machine that consists of a bar that pivots, or rotates, around a fixed point
wheel and scale a simple machine that consists of an axle attached to the center of a larger wheel, so that the shaft and wheel rotate together
pulley a simple machine that consists of a grooved wheel with a rope or cable wrapped around it
complex machine two or more simple machines working together
efficiency the ratio of output work to input work
sound wave a longitudinal wave that can travel only through matter
pitch the perception of how high or low a sound is; related to the frequency of a sound wave
echo a reflected sound wave

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