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weight changes when gravitational forces changes

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a measure of the amount of matter in an object

# data[].attributes.body
a measure of the gravitational force exerted on an object; its value can change with the location of the object in the universe

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a force of attraction between objects that is due to their masses

All matter has mass. Gravity is a result of mass.

Force increases as mass increases

gravitation force decreases as distance increases

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harmful -holes in clothes
helpful - cars brake

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a force that opposes motion between two surfaces that are in contact

more force more friction

the rougher the surface the more friction

static friction means not moving the friction balances the force exerted disappears once object moves

kinetic friction means moving slide or roll

reduce friction by using a lubricant, rolling, smooth surface

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0 N not moving

NOT 0 N moving

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magnet
gravity

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the SI unit for force force (symbol, N)

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the combination of all of the net forces acting on an object

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a push or pull exerted on an object in order to change the motion of the object; force has size and direction

expressed in newtons

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trees
buildings

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the rate at which velocity changes over time.

average acceleration=final velocity - starting velocity/time it takes to change to change velocity

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the speed of an object in a particular direction.

Two factors speed and direction

add/subtract velocities for resultant velocity

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the distance traveled divided by the time interval during which the motion occurred.

measured in meters per second

average speed= total distance/total

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an object's change in position relative to a reference point