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Level 49

## Ignore words

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friction
a contact force; type of force between two touching surfaces
inertia
_______ is the property of an object that leads it to resist any change in motion
balanced force
Equal forces acting on an object in opposite directions
unbalanced force
force acting on an object that causes a change
lubricants
materials that reduce friction
net force
Acceleration depends on the
gravity
(physics) the force of attraction between all masses in the universe
First Law of Motion
An object at rest or in motion will remain at rest or in motion unless acted upon by an unbalanced force.
Newton's second law
Acceleration is produced when a force acts on a mass, the greater the mass, the more force is required to accelerate the object.
Simple Machines
Tools that make work easier.
6 Simple Machines
lever, pulley, screw, wheel and axle, inclined plane, wedge
Wedge
A simple machine that is an inclined plane with one or two sloping sides.
wheel and axle
A rod attached to a wheel. It makes it easier to move or turn things.
Screw
A simple machine that is an inclined plane wrapped around a central cylinder to form a spiral
pulley
a grooved wheel with a rope running along the groove
Compound Machine
A combination of two or more simple machines.
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.
lever
a rigid bar or board that is free to move around a fixed point called a fulcrum
sliding friction
friction caused by moving two flat surfaces against each other
Rolling Friction
Friction that occurs when an object rolls over a surface
fluid friction
a type of friction that occurs when a solid object moves through a gas or liquid
Force/mass
acceleration
motion
An object is moving if its position relative to a fixed point is changing.
acceleration
(physics) a rate of change of velocity
Reference Point
A _______ is a place or object used for comparison to determine if something is in motion.
Power
(physics) the rate of doing work
kinetic energy
a running dog
distance/time
speed
Velocity
a speed in a particular direction.
Instantaneous Speed
Magnitude of instantaneous velocity