Chapter 7 Motion

Motion A change in position

Elapsed Time The length of time that passes from one event to another

Speed The rate at which the position of an object changes

Distance The length of the path between two points

Speed Calculation Distance 50 yards Average speed = ________ 8.771 = __________ Time 5.7 sec

Distance Calculation Distance = speed X time 50yards = 8.771 X 5.7 Distance =_________x 5.7 sec 1 hour

Calculating Time Speed = distance ___________ Time 50 yds _______ = 5.7 8.771

Constant Speed Speed that does not change

Velocity The speed and direction in which an object is moving

Acceleration The rate of change in velocity

Deceleration The rate of slowdown Acceleration = change in speed / change in time Acceleration= 40km/1hr divided by 5sec/1 Acceleration= 40km / 1hr X 1/5 sec Acceleration= 8km/hr per sec

Force A push or a pull

Friction A force that opposes motion and that occurs when things slide or roll over each other.

The first law of motion Newtons first law of motion states that if no force acts on a object at rest, it will remain at rest. The law also says that if the object is moving, it will continue moving at the same speed and in the same direction if no force acts on it.

Inertia The tendency of an object to resist changes in its motion.

Second Law of Motion The amount of force needed to produce a given change in the needed to produce a given change in the motion of an object depends on the mass of object. The larger the mass, the more force is needed to give it a certain acceleration.

Gravity The force of attention between any two objects that have mass

Law of Universal gravitation Gravitational Force depends on the mass of the two objects involved and on the distance between them.