Science
This is the Study Guide for the entire Forces & Motion Unit
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Forces & Motion Study Guide
Speed/rate - measures the distance an object travels in a specific amount of time
speed=distance/time
Velocity – the rate of speed of an object in one direction
Motion – an object changing position over time
measured in centimeters, meters, or kilometers
graphing data helps make motion easier to understand
Force – a push or a pull on an object
applying a force can change a motion
Balanced Force – causes an object to remain in place, forces that are equal in force and opposite in size
Unbalanced Force – causes and object to start moving, stop moving or change direction
the total force of an object is moving in one direction
Inertia – an objects resistance to a change in motion
an object at rest will remain at rest and an object in motion will remain in motion unless an outside force acts
upon it
a massive object has a lot of inertia, while a smaller object has less inertia
Newton’s 1st Law – also known as the law of inertia
An object at rest will remain at rest and an object in motion will remain in motion unless acted on by an
unbalanced force. Why your body goes forward when a car stops suddenly
Newton’s 2nd Law – also known as the law of acceleration
Acceleration is produced when a force acts on a mass. The greater the mass of the object, the greater the
amount of force needed to accelerate the object.
Force = Mass x Acceleration
Newton’s 3rd Law – For every action there is an equal and opposite reaction
If a force pushes in one direction, an equal force pushes in the opposite direction
Gravity – the attraction of all objects toward each other
The larger the two objects and the closer they are, the greater the gravitational attraction between the objects
The moon gravitates around the earth
All objects on earth are pulled toward the center of Earth equally
a computer and a marble, dropped off a building at the same time, will hit the ground at the exact same time
Mass – describes how much matter an object contains, typically measured in grams
will not change based on location, same on Pluto and Jupiter
Weight – a force that gravitation exerts on any object
the amount of gravity determines weight
weight can vary depending on which planet you are on, weight on Jupiter is greater than Earth, weight on the
moon is 1/6 of your weight on Earth
Friction – occurs when two objects rub against each other, acts in the opposite direction to the motion of the moving
object. Whenever two surfaces touch, friction is created.
This is a force that causes one of the objects to slow or come to a stop
Grease or oil can reduce friction (lubricant)
Without friction between the ground and our shoes, we would slip and slide and not be able to walk
Acceleration – rate of change of velocity
velocity is either increasing or decreasing or changing direction
Slope – the distance covered while coming down from a height
The steeper the slope, the faster the skier accelerates. The faster the skier accelerates, the greater the skier’s
speed.
Work – a force moving an object over a distance
the object must be moved in the same direction as the force applied to the object
Simple Machines: make work easier by reducing the amount of effort needed
It either spreads the effort over a greater amount of time or a greater distance
Inclined Plane: slanted surface, also called a ramp
helps us move an object from a low place to a high place
ex. moving van ramp, handicap ramp,
Wedge: has at least one slanted side
used to push things apart
ex. door stop, head of an axe
Screw: an inclined plane wrapped around a center shaft
used to hold things together
ex. bottle top, drill bit
Lever: it’s a bar of wood or metal that sits on a fulcrum or pivoting point
Pushing down on one end of the lever pushes up the other end
used to move heavy objects
ex. see-saw, shovel
Pulley: a grooved wheel and rope
used to easily lift a load
ex. construction crane, flag pole,
Wheel & Axle: a system that includes two wheels and a rod or axle in between them
used to transport items
ex. wagon wheels, car tires