NEWTON'S LAW.pptx

8/14/2019 NEWTON'S LAW.pptx

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Newtons Law of Motion


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Newtons Law of Motion

Standard of Competence

Basic Competence

Learning Objectives

Learning Material


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Standard of Competence

3. Comprehending work, force,and energy role in daily life.


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Basic Competence

3.3 Apply Newtons laws to

explain everyday phenomena.


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Learning Objectives

1. State the first of Newtons laws on motion.

2. Explain the relation between force, mass, and

acceleration.

3. Apply the Second Newtons laws in everyday life.

4. Observe the effects of air resistance.

5. Analyze action and reaction forces.

6. Explain the application of Newtons Thirdlaws in

everyday life.


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NEWTONS LAW OF MOTION

NEWTONS FIRST LAW

NEWTONS SECOND LAW

NEWTONS THIRD LAW


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Newtons 1stLaw


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Newtons 1stLaw of Motion

Newtons 1stlaw of motion states:

An object at rest will remain at rest,

-and-

an object moving at a constant velocity will

continue moving at a constant velocity,-UNLESS-

it is acted upon by an unbalanced force.


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Thats because larger objects have moreinertia (more resistance to a change in

their motion)!

Objects resist any change to their motion!This resistance is called INERTIA.

Which one would be easier to push?

or

BASICALLY
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Inside a moving vehicle, everything ismoving at the same velocity your body,the objects in the car, and the caritself.

What would happen to the things insidethe car if the car hit a wall?

Thats because things moving at a

constant velocity will stay at a constantvelocity unless acted upon by anunbalanced force.

The car was acted upon by an outsideforce the force of the wall hitting thecar.

The person inside the car wasnt hit by theforce of the wall, so he kept moving at thesame speed and in the same direction.


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Explain this animation:

The truck is stopped by the force ofthe impact with the car, but the laddercontinues to move at its original speedand in its original direction because of

inertia.


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Newtons 2ndLaw


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NEWTONS SECOND LAW

Video
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Acceleration is directly proportional to

magnitude of the force

Acceleration is inversely proportional to the

mass of the body.


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Acceleration is directly proportional to the net

force acting on it, and inversely proportional to

its mass.

or

State of Newtons Second Law :

Where : a = acceleration (m/s )

m = mass (kg)

F = force (N)

2


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Newtons 3rdLaw


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Which forces are acting to get thisguy up in the air?

His feet pushDOWN on theground.

But wait How can his downward push

cause his upward motion? NO WAY!


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Which forces are acting to get thisguy up in the air?

His feet push DOWN onthe ground.

There must be a force pushing UP! The force of the ground pushes him UP!

The ground pushes UP onthe man.


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Newtons 3rdlaw says that: For every action

force, there is an equal and opposite

reaction force.

Newtons 3rdLaw of Motion

Action Force: Mans feetpush DOWN on the ground.

Reaction Force: Ground

pushes UP on the man.

The forces, like ALLforces, act in PAIRS!


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Lets Demonstrate

Stand up and face a partner with

your palms touching.

Push on your partners hands.Dont move your feet. The firstpartner to step back loses

How can Newtons third law

explain what happens?


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Explain this animation using

Newtons third law.


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The mans foot exerts a backwardpush on the boat (action force),while the boat exerts a forward

push on the man (reaction force).

A PAIR OF FORCES:EQUAL FORCES, BUT

IN OPPOSITEDIRECTIONS


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Identify the force pairs in eachsituation

A person fires a rifle.

Action Force gun pushesthe bullet out at highspeed.

Reaction Force thebullet pushes back on thegun (recoil).


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A space shuttle lifts off.

Action Force enginepushes gases down & out.

Reaction Force the

gases push the rocket up.*This upward force must bestronger than gravity pulling

down on the rocket!


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A person stands still.

Action Force gravitypulls the person down tothe floor.

Reaction Force the floorpushes up on the person.

*You dont need MOTION for

force pairs. They areever where!


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If forces are equal and in oppositedirections, why dont they cancel out

(and balance)?

Forces only cancelif they

act on the same object.(Think about a tug of war all forces act on the rope).

These forces are actingon different objects!

These forces are acting on

different objects!Action Force Rocketengine pushing on gases.

Reaction Force Gasespush on the rocket.


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NEWTON'S LAW.pptx