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## Ignore words

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First Law
An object at rest will stay at rest and an object at motion will remain in motion unless acted upon by an outside force.
inertia
_______ is the property of an object that leads it to resist any change in motion
The Newton
Standard Unit for force
Second Law
The net force needed to change an object's motion is equal to its mass times its acceleration-OR- The acceleration of an object depends on its mass and the net force acting on it.
Third Law
When one object exerts a force on an object, the second object, the second object exerts a force equal in size and opposite in direction back on the first object
force
(interactions between two objects)
friction
a contact force; type of force between two touching surfaces
fluid friction
a type of friction that occurs when a solid object moves through a gas or liquid
sliding friction
friction caused by moving two flat surfaces against each other
Rolling Friction
Friction that occurs when an object rolls over a surface
gravity
(physics) the force of attraction between all masses in the universe
Contact force
A force that "touches" or comes in contact with the system
Reference Point
A _______ is a place or object used for comparison to determine if something is in motion.
Speed
Units: cm/s, m/s, mi/hr, km/s ...
acceleration
(physics) a rate of change of velocity
Positive Acceleration
An increase in velocity
Negative Acceleration
A decrease in velocity
work
a force acting upon an object to cause a displacement. (key words: force, displacement, and cause)
Power
(physics) the rate of doing work
Energy
(physics) the capacity of a physical system to do work
gravitational potential energy
an icicle hanging from a rooftop
Mechanical Energy
position and movement of an object
Machine
A device that makes doing work easier.
Efficiency
_______ compares the amount of output work to the input work.
Simple Machine
A machine that does work with only one movement.
Compound Machine
A combination of two or more simple machines.
pulley
a grooved wheel with a rope running along the groove
Wedge
A simple machine that is an inclined plane with one or two sloping sides.
Inclined Plane
A flat surface set at an angle or an incline with no moving parts that is able to lift objects by pushing or pulling the load.
Screw
A simple machine that is an inclined plane wrapped around a central cylinder to form a spiral
Wheel and Axel
A simple machine with a center rod or axle joined to a wheel