Newton's Laws of Motion Isaac Newton (17th century scientist)

Sir Isaac Newton Lived from in England. He was a dedicated physicist and mathematician, and is considered to be one of the most brilliant scientists of all time. He is most famous for his three laws of motion and his universal law of gravitation, but did much more.

Mass & Weight Mass is the amount of “stuff” or matter that an object contains. Weight and Mass are different. Weight, or how much an object weighs, depends on the amount of gravity acting upon it. –Ex. You weigh less on the moon then on Earth. Weight on other worlds

Force A force is what we call a push or a pull, or any action that has the ability to change motion of an object. The metric unit used to describe force is called the Newton (N). One Newton is equal to: 1 Kg x 1 m/s/s Thus, one Newton of force causes a one kilogram object to accelerate at a rate of one meter per second squared. Your weight in NewtonsYour weight in Newtons!!!

Newton’s First Law of Motion An object at rest will remain at rest, and an object in motion will remain in motion unless acted upon by an unbalanced force. –When you roll a ball, why doesn’t it roll on forever? FRICTION –This concept is also referred to as the Law of Inertia

The Law of Inertia

Inertia Inertia is defined as the property of an object to resist changing its state of motion. The amount of inertia that an object has depends on the amount of mass that it has. The more massive the object is the harder it is to move or stop.

Balanced and Unbalanced Forces The motion of all objects depends on the total of all forces acting on the object. We call the total of all forces the net force.

Balanced and Unbalanced Forces

Concept Check: Mac and Tosh are arguing in the cafeteria. Mac says that if he flings the Jell-O with a greater speed it will have a greater inertia. Tosh argues that inertia does not depend upon speed, but rather upon mass. Who do you agree with? Explain why.

Concept Check: Ben Tooclose is being chased through the woods by a massive bull moose which he was attempting to photograph. If Ben makes a zigzag pattern through the woods, he will be able to use the large mass of the moose to his own advantage. Explain this in terms of inertia and Newton's first law of motion.

Concept Check: Mr. Wegley spends most Sunday afternoons at rest on the sofa, watching pro football games and consuming large quantities of food. What effect (if any) does this practice have upon his inertia? Explain.

Newton’s Second Law of Motion Newton’s second law relates the applied force on an object, the mass of an object and the acceleration. It states: F = M x A Another form of this equation says: A= Fforce causes acceleration M mass resists acceleration ___

Newton’s second law There are three main ideas related to Newton’s Second Law: 1.Acceleration is the result of unbalanced forces. 2.A larger force makes a proportionally larger acceleration. 3.Acceleration is inversely proportional to mass.

Newton’s Third Law of Motion For every action there is an equal and opposite reaction. If you push on something it pushes back with the exact same force. Forces come in pairs

Newton’s Third Law of Motion Sometimes the reaction force is noticeable and causes motion –(ex – recoil from a gun) Sometimes it is more subtle, but forces ALWAYS act in pairs. –(ex - sitting in a chair, walking)

Solving Problems A woman with a weight of 500 newtons is sitting on a chair. Describe one action- reaction pair of forces in this situation.

Concept Check: Explain the net force in each graph

Videos Football and HockeyFootballHockey Newtons Three Laws