# Shared Flashcard Set

## Details

SCIENCE
Forces and Motion
32
Science
8th Grade
10/05/2012

## Cards Return to Set Details

Term
 FORCE
Definition
 push or pull of an object
Term
 NET FORCE
Definition
 combination of all of the forces acting on an object (tug-o-war     2 sets of forces on the rope)
Term
 BALANCED FORCES
Definition
 These occur when the net force on an object is Zero.  The object does not move in any direction.
Term
 UNBALANCED FORCES
Definition
 Occur when the net force on an object is not zero.  The object moves because one or more of the forces is (are) greater than the others.
Term
 NEWTON
Definition
 unit we use to measure forces
Term
 MOTION
Definition
 when an object changes its position over time
Term
 POINT OF REFERENCE
Definition
 an object that appears to stay in place and you compare the motion of another object to it
Term
 SPEED
Definition
 how fast something moves
Term
 VELOCITY
Definition
 speed of an object in a particular direction
Term
 ACCELERATION
Definition
 a change in velocity - either speed or direction or both
Term
 POSITIVE ACCELERATION
Definition
 when something speeds up
Term
 NEGATIVE ACCELERATION
Definition
 (deceleration) when something slows down
Term
 DIRECTIONAL ACCELERATION
Definition
 when something changes direction
Term
 FRICTION
Definition
 a force that opposes (works against) motion between two surfaces that are touching
Term
 SLIDING FRICTION
Definition
 this happens when one flat surface moves across another flat surface
Term
 ROLLING FRICTION
Definition
 happens when a round object rolls across a surface
Term
 FLUID FRICTION
Definition
 occurs between liquids or gases and other objects
Term
 STATIC FRICTION
Definition
 this type of friction is observed when objects are not moving at all
Term
 WEIGHT
Definition
 a measure of how much force gravity is pulling on an object;   how much force you would need to pick up an object from the ground
Term
 GRAVITY
Definition
 force of attraction between two objects that is there just because there is matter there
Term
 What is the SI unit for force?
Definition
 the newton, abbreviated N
Term
 relative directional terms
Definition
 right forward backward to the left upward downward
Term
 "Law of Universal Gravitation"
Definition
 the larger the masses of the objects, the closer they are and the stronger the gravitational force between them
Term
 Who came up with the Law of Universal Gravitation?
Definition
 Sir Isaac Newton
Term
 What causes friction?
Definition
 hills and valleys of one surface sticking against the hills and valleys of the other surface
Term
 Ways to reduce friction
Definition
 using lubricant making the surfaces smoother use wheels that create rolling friction instead of sliding friction
Term
 formula for average speed
Definition
 s=d/t
Term
 formula for distance
Definition
 d=s (x) t
Term
 formula for time
Definition
 t=d/s
Term
 speed =
Definition
 distance divded by the amount of time it took to cover that distance
Term
 distance =
Definition
 speed (x) time
Term
 time =
Definition
 distance divided by speed
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