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 |