NEWTON’S LAWS

Newton “Father of modern science”https://www.youtube.com/watch?v=danYFxGnFxQ

(My Man, Sir Isaac Newton) 1:58 minhttps://www.youtube.com/watch?v=UuFAfD7Krhk

(biography Isaac Newton) 1:30 minhttp://

www.pbs.org/wgbh/nova/physics/newton-legacy.html For more info on Newton

SIR ISAAC NEWTON

an English physicist and mathematician who is widely regarded as one of the most influential scientists of all time and as a key figure in the scientific revolution

laid the foundations for most of classical mechanics formulated the laws of motion and universal

gravitation that dominated scientists' view of the physical universe for the next three centuries.

He also demonstrated that the motion of objects on the Earth and that of celestial bodies could be described by the same principles.

WHO WAS NEWTON?

Why can’t expecting woman ride all the adventure rides at Universal?

Why is a seatbelt a good idea?Why do I feel sick on a roller coaster?http://www.youtube.com/watch?v=ACmBFMQqqloPredict what will happen next

FIRST LAW OR LAW OF INERTIA

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

There are two parts to this statement---one that predicts the behavior of stationary objects and the other that predicts the behavior of moving objects.

1ST LAW

What is inertia? an objects tendency to avoid change Property of matter

History Notes: Newton's conception of inertia stood in direct opposition to

more popular conceptions about motion. The dominant thought prior to Newton's day was that it was

the natural tendency of objects to come to a rest position. The thought at the time was that moving objects would

eventually stop moving; a force was necessary to keep an object moving. But if left to itself, a moving object would eventually come to rest and an object at rest would stay at rest

1ST LAW IS SAME AS LAW OF INERTIA

Fred spends most Sunday afternoons at rest on the sofa, watching pro football games and consuming large quantities of food. What eff ect (if any) does this practice have upon his inertia? Fred's inertia will increase! Fred will increase his mass if

he makes a habit of this. And if his mass increases, then his inertia increases.

CRITICAL APPLICATION

Ping pong vs bowling ball… both on a table. Which is easier to move?

CRITICAL APPLICATION

 Two bricks are resting on edge of the lab table. Shirley acquires an intense desire to know which of the two bricks are most massive. Since Shirley is vertically challenged, she is unable to reach high enough and lift the bricks; she can however reach high enough to give the bricks a push. Discuss how the process of pushing the bricks will allow Shirley to determine which of the two bricks is most massive. What diff erence will Shirley observe and how can this observation lead to the necessary conclusion? The bricks, like any object, possess inertia. That is, the bricks

will resist changes in their state of motion. If Shirley gives them a push, then the bricks will offer resistance to this push. The one with the most mass will be the one with the most inertia. This will be the brick which offers the most resistance. This very method of detecting the mass of an object can be used on Earth as well as in locations where gravitational forces are negligible for bricks.

CRITICAL APPLICATION

But do some objects have more of a tendency to resist changes than others? Absolutely yes!

The tendency of an object to resist changes in its state of motion varies with mass.

Mass is that quantity that is solely dependent upon the inertia of an object.

A more massive object has a greater tendency to resist changes in its state of motion

1ST LAW

Have you ever observed the behavior of coff ee in a coff ee cup fi lled to the rim while starting a car from rest or while bringing a car to rest from a state of motion?

Coff ee "keeps on doing what it is doing." When you accelerate a car from rest, the road provides an

unbalanced force on the spinning wheels to push the car forward; yet the coff ee (that was at rest) wants to stay at rest.

While the car accelerates forward, the coff ee remains in the same position; subsequently, the car accelerates out from under the coff ee and the coff ee spills in your lap.

On the other hand, when braking from a state of motion the coff ee continues forward with the same speed and in the same direction , ultimately hitting the windshield or the dash. Coff ee in motion stays in motion.

1ST LAW

http://www.youtube.com/watch?feature=player_embedded&v=--MDILG7Znk

INERTIA TRICK

Newton's second law of motion pertains to the behavior of objects for which all existing forces are not balanced.

The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object.

The acceleration of an object depends directly upon the net force acting upon the object, and inversely upon the mass of the object.

As the force acting upon an object is increased, the acceleration of the object is increased.

As the mass of an object is increased, the acceleration of the object is decreased.

2ND LAW

2ND LAW

The acceleration is directly proportional to the net force

the net force equals mass times accelerationthe acceleration in the same direction as the net

forcean acceleration is produced by a net force. The NET

FORCE. It is important to remember this distinction. Do not use the value of merely "any 'ole force" in the

above equation. Fnet=ma

2ND LAW

Example problems:What net force is required to

accelerate a car at a rate of 2 m/s2 if the car has a mass of 3,000 kg?

A10 kg bowling ball would require what force to accelerate down an alleyway at a rate of 3 m/s2?

Sally 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?

What is the mass of a falling rock if it produces a force of 147 N?

2ND LAW

For every action there is an equal and opposite reaction

The statement means that in every interaction, there is a pair of forces acting on the two interacting objects.

The size of the forces on the fi rst object equals the size of the force on the second object.

The direction of the force on the fi rst object is opposite to the direction of the force on the second object.

Forces always come in pairs - equal and opposite action-reaction force pairs.

3RD LAW

http://gpb.pbslearningmedia.org/resource/kqedq11.sci.newtonslawsofmotion/newtons-laws-of-motion/

A variety of action-reaction force pairs are evident in nature.

Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. But a push on the water will only serve to accelerate the

water. Since forces result from mutual interactions, the water must

also be pushing the fish forwards, propelling the fish through the water.

The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards).

For every action, there is an equal (in size) and opposite (in direction) reaction force. Action-reaction force pairs make it possible for fish to swim.

3RD LAW

Consider the motion of a car on the way to school. A car is equipped with wheels that spin. As the wheels spin, they grip the road and push the

road backwards. Since forces result from mutual interactions, the road

must also be pushing the wheels forward. The size of the force on the road equals the size of

the force on the wheels (or car); the direction of the force on the road (backwards) is opposite the direction of the force on the wheels (forwards).

For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for cars to move along a roadway surface.

3RD LAW

Mythbusters and flying fl ight attendant Identify how all three laws are in action in the clip

WRITE THESE DOWN!!!https://www.youtube.com/watch?v=peZ7wZ5JXRE

RECAP OF NEWTON’S LAWS