NEWTON’S LAWS OF MOTION

Newton’s LawsNewton’s Laws are all about force

and motion. Force is a push or pull; something that changes the motion of an object

Types of forceGravity: Force of attraction between two masses.

Friction: Force that resists motion between two surfaces.

Balanced and unbalanced forcesIf the net force on an object is

zero, the forces acting on the object are balanced.

Overall force acting on an object when forces are combined is the net force.

An Unbalanced Force produces an non-zero net force, which changes the object’s motion.

Newton’s 1st LawNewton’s 1st Law: An object at rest will remain at rest, and an object in motion will remain in motion with the same velocity unless an unbalanced force acts upon it.

Newton’s 1st Law Anytime you read about a

situation where something is at rest and then it starts moving or is moving and then it stops, it is talking about Newton’s 1st Law.

Newton’s 1st LawThere is a box that is sitting on

the floor at rest. It will remain at rest until somebody pushes it.

At rest… In motion…

Newton’s 1st Law You are driving in a car with no seat belt on. You see

a family of ducks and slam on your brakes to avoid hitting them. Since you are not wearing your seat belt, you fly out of the car (remain in motion) until you hit the ground (an unbalanced force).

AHH!

Ouch

In motion… At rest…

Inertia (ih-NER-shuh)Inertia is the resistance of an object to a change in the speed or direction of its motion.

How does this apply to Newton’s 1st law?◦The first law describes the tendency

of objects to resist changes in motion.

◦AKA they’re one in the same.

Newton’s Second Law states that the acceleration of an object increases with increased force and decreases with with increased mass.

Force = mass x acceleration

Newton’s Second Law

What force is needed to accelerate a 10 kg shopping cart 3 m/s2?

Force = mass x accelerationMass = 10 kg, Acceleration =3 m/s2

F= 10 kg x 3 m/s2

Answer: F=30 N

Newton’s 2nd Law—Apply the Knowledge

What force is needed to accelerate a 20 kg boulder to 2 m/s2?

Force = mass x accelerationMass = 20 kg, Acceleration =2 m/s2

F= 20 kg x 2 m/s2

Answer: F=40 N

CFU

PRACTICE QUESTIONS (complete on your handout)

A 10 kg bowling ball would require what force to accelerate down an alleyway at a rate of 3 m/s2?

PRACTICE QUESTIONS (complete on your handout)

Victor has a car that accelerates at 5 m/s2. If the car has a mass of 1000 kg, how much force does the car produce?

Sometimes referred to as law of “EQUAL and OPPOSITE”

For every reaction, there is an “equal and opposite” reaction

What ever happens, there is an exact (but opposite) force that happens as well.

Newton’s Third Law—in more simple terms

So if Nixon pushes against a wall with a force of 25N, how much force does the wall exert on him, and in what direction?

25 N

CFU…

The force that is exerted on an object and the force that exerts back are known as action-reaction pairs.

Example: When Abed bangs his toe into the leg of the table, the same amount of force he exerts on the table is exerted back on his toe.

Action-Reaction Pairs

Click the link below to sum up Newton’s Laws of Motion http://www.d123.org/olhms/dedie

/documents/2-3Forces.pdf