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Motion and Energy
Chapter 1-4
| 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 |