Newton’s Laws Marti Andreski De La Salle HS

Isaac Newton More than 300 years ago, Sir Isaac Newton explained the way in which forces (pushes and pulls) influence motion

Newton, the Man Born in 1642 (Jan 4, 1643 on the adjusted Gregorian Calendar) (shares birthdate of another not-so-famous physicist, though 318 years later!) English physicist and mathematician born to a poor farming family

Newton’s Four Rules for Scientific Reasoning These rules were stated in the Principia (1) we are to admit no more causes of natural things such as are both true and sufficient to explain their appearances, (2) the same natural effects must be assigned to the same causes, (3) qualities of bodies are to be esteemed as universal, and (4) propositions deduced from observation of phenomena should be viewed as accurate until other phenomena contradict them.

Newton’s Contributions Invented calculus Developed a theory about "elements" -consisted of different arrangements of atoms, and atoms consisted of small, hard, billiard ball-like particles Had countless other important thoughts in Astronomy, Physics, Chemistry (White light consists of all the other colors; Law of Universal Gravitation; Laws of Motion; his book, Principia, is recognized as the greatest scientific book ever written!) The Latin inscription on Newton's tomb, proclaims, "Mortals! Rejoice at so great an ornament to the human race!"

Newton’s Quotations To explain all nature is too difficult a task for any one man or even for any one age. `Tis much better to do a little with certainty, and leave the rest for others that come after you, than to explain all things. If I have been able to see further, it was only because I stood on the shoulders of giants. I know not what I appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell, whilst the great ocean of truth lay all undiscovered before me. Quoted in D Brewster, Memoirs of Newton Numero pondere et mensura Deus omnia condidit God created everything by number, weight and measure.

Some Basic Definitions Force: A push or pull Newton (N): the unit used to measure force; equal to 1 kg. m/s 2 Inertia: the tendency of an object to resist a change in its motion Equilibrium: an object is in equilibrium if it is at rest or moving at constant velocity.

First Law of Motion “An object at rest remains at rest and an object in motion remains in motion unless acted upon by an outside force” Aka: “The Law of Inertia”

EXAMPLE: 1 st Law We wear seatbelts because of the 1 st law of motion. If our car travels at a rate of 55 mph, then we, too travel at that rate. However, the car has brakes and unless we wear seatbelts, we don’t have brakes. We would continue moving at 55 mph if the car came to a sudden stop. /newtlaws/cci.htmlhttp://www2.glenbrook.k12.il.us/gbssci/phys/mmedia /newtlaws/cci.html

Second Law of Motion F = ma “A net force on a mass gives rise to an acceleration”

EXAMPLE: 2 nd Law Stretch a rubber band as if to shoot it. The more we pull it back, the greater the force we’re applying to the rubber band. When we release the rubber band, it has a greater acceleration with the greater force.

Third Law of Motion “For every action, there is an equal and opposite reaction”

EXAMPLE: 3 rd Law Stretch a string between two points in the room, fitting a straw on the string. Blow up a balloon, holding the end closed with your fingers, and tape the balloon to the straw as shown in the diagram. Let the balloon go. Air is released from the balloon and allows the balloon to move forward.

DEMOS: Newton’s Laws You will be shown a number of demonstrations dealing with motion. In your lab portfolio, make a large data table, leaving room for comments, etc. Follow the format shown on the next slide.

DEMOS - a Name of Demo DescriptionWhich Law? Explanation Penny & Hoop Ballistics Car Penny & Drill Wire Hanger

DEMOS -b Name of Demo DescriptionWhich Law? Explanation Water Rocket RubberBand Rocket Pig Shooter Tablecloth Trick