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