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Laws of ForceLaws of Force
Mr. Dunnum
Physical Science
What is force?
Force is simply a push or pull All forces have both size and direction Forces are everywhere Anytime you see something moving, you
can be sure that its motion created by a force
How do we measure force?
Scientist express force by using a unit called Newton's
The more the Newton's the greater the force
Net force?
What is net force?
Net force is the result of combining all the forces exerted on an object
Same direction you add them
Opposite directions you subtract them
Unbalanced and BalancedForces
Unbalanced forces When the net forces
of an object is not zero then it is an unbalanced force.
Unbalanced forces cause nonmoving objects to start moving
Balanced forces
When the net forces equal zero then the forces are balanced
Balanced forces don’t cause objects to move
Newton's first law
If an object is at rest it will remain at rest unless it is affected by an outside force, if an object is moving it will remain moving until it is stopped by an outside force.
Friction
Force that opposes motion between two surfaces
Friction occurs because the surface of any object is rough
A rougher surface creates more friction
The more force the more friction
Sliding/ Rolling Friction
Sliding Friction Takes more effort and
force to move objects by sliding
Ex. Moving furniture
Rolling Friction
Is important to all means of transportation
The friction is smaller and easier to move than sliding
Fluid/Static Friction
Fluid Friction Also less than sliding
friction Swimmers have to
overcome this when swimming
Static Friction
Prevents an object from moving when force is applied
Ex. Moving a refrigerator
Helpful/HarmfulFriction
Helpful Car- friction helps push the car down the
road. It also helps us stop the car with the brakes Harmful Car- Cause wear and tear on the motor of
the car.
Newton's Second Law
An object acted upon by a force will accelerate in the direction of the force
Acceleration= net force
mass
F=MA
What is Gravity?
Gravity is the force of attraction between two objects
All matter is affected by gravity
Gravity pulls you down, air resistance pushes you up
Gravity Con.
Small masses have a small gravitational force
The larger masses have a larger gravitational force
If the distance between the two objects is in creased then the gravitational force is reduced
Weight and Mass
Weight Weight is the
gravitational force exerted on an object
Weight changes when the gravitational force changes
Weight is measured on a spring scale
Mass
The amount of matter in an object, and its value does not change
If moved to Jupiter the weight would change, but not the mass
Measured by a balance
Newton's Third Law
For every action there is an equal, but opposite reaction
Example when you push a wall it pushes back with the same force
Examples of Newton’s 3rd Law
Bumper cars
Getting oil changed
Diving in a pool
Dunking a basketball
Free fall and Weightlessness
Free Fall An object is in free
fall when the only force acting on it is gravity
Weightlessness
Is the condition that occurs in free fall when the weight of an object seems to be zero