September 28, Newton's Laws of Motion

Transcription

1 Pull Newton's Laws of Motion

2 Sir Issac Newton His 1687 publication of the Principia is considered to be among the most influential books in the history of science. Considered by many to be the most influential scientist in history. Most remembered for his 3 laws of motion.

3 NEWTON'S 1ST LAW OF MOTION An object at rest remains at rest, and an object in motion remains in motion unless acted on by an unbalanced force.

4 INERTIA The tendency of an object to resist being moved, or, if the object is moving, to resist a change in speed or direction until an outside force acts on the object

5 Example: You are standing on a scooter, you will not go anywhere unless you push off the ground. Why?

6 Another Example: Which of the following objects have inertia? THE MOON ORBITING EARTH A BOOK AND AN APPLE ON A DESK A FALLING SKYDIVER

7 ALL OF THEM HAVE INERITA!!!!!!!! THE MOON ORBITING EARTH A BOOK AND AN APPLE ON A DESK A FALLING SKYDIVER Kicking Something

8 MOMENTUM * Momentum deals with an object's inertia. The higher the velocity and mass, the more momentum an object has. Momentum = mass X velocity measured in kg * m/s The Law of Conservation of Momentum states: The total momentum of any group of objects remains the same unless outside forces act on the objects. When 2 objects collide in the absence of friction, momentum is not lost.

9 What affects Acceleration? What does this boy need to do in order to get up the hill? The more force he applies (pedaling) the further he will travel

10 What affects Acceleration? What will happen if we add a backpack full of textbooks? What will he have to do in order to make it up the hill? He will have to pedal harder (apply greater force) in order to reach the same speed.

11 NEWTON'S 2ND LAW OF MOTION The acceleration of an object depends on themass of the object and the amount of force applied. Written as: FORCE = MASS x ACCELERATION or F=MxA

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13 What affects Acceleration? Sir Isaac Newton understood that changing the force isn't the only thing that affects acceleration. He also understood that MASS affects acceleration.

14 How about in football? How could the football player with the small mass knock over the football player with the large mass?

15 ANSWER THE FOOTBALL PLAYER WITH THE SMALLER MASS WOULD HAVE TO HAVE GREATER ACCELERATION.

16 What does it take to make an object move? What if both of these vehicles ran out of gas? Would you rather push the small compact car or the large truck?

17 ANSWER OBVIOUSLY YOU'D RATHER PUSH THE SMALL COMPACT CAR BECAUSE IT HAS A SMALL MASS AND A SMALLER INITIAL INERTIA

18 Newton's 3RD Law OF MOTION Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. Or: For every action, Hitting there Something is an equal and opposite reaction.

19 For Example What is the action and what is the equal and opposite reaction in this picture? Hitting Something

20 ANSWER FUEL SHOOTS OUT THE BACK, AND THE ROCKET GOES UP. Hitting Something

21 Another Example What is the action and what is the equal and opposite reaction in this picture? Hitting Something

22 REVIEW 1. WHAT IS NEWTON'S 1ST LAW, AND GIVE AN EXAMPLE OF IT IN EVERYDAY LIFE. 2. WHAT IS NEWTON'S 2ND LAW, AND GIVE AN EXAMPLE OF IT IN EVERYDAY LIFE. 3. WHAT IS NEWTON'S 3RD LAW, AND GIVE AN EXAMPLE OF IT IN EVERYDAY LIFE.

23 ADDITIONAL RESOURCES: BRAINPOP: SIR ISSAC NEWTON NEWTON'S LAWS OF MOTION

24 NEWTON OLYMPICS FOR EACH STATION YOU MUST INCLUDE THE FOLLOWING IN YOUR REPORT: 1. Title of the event: example: ROLLING CARTS 2. When it says, "IN YOUR REPORT..." in the instructions, you must answer that question or collect that data 3. The final statement always says, "In your report, identify which of Newton's laws is most applicable to this event and explain why". You must answer this. A COUPLE MORE THINGS YOU WILL HAVE 5 MINUTES AT EACH STATION, WHICH INCLUDES ROTATING, SO BE SURE TO WORK STEADILY. READ ALL THE INSTRUCTIONS CAREFULLY FIRST, THEN GO BACK THROUGH AND PERFORM THE EVENT

25 Momentum of 1 Moving Object * When a moving object hits a stopped object its motion transfers to the stopped object, and the first moving object will stop moving.

26 Momentum of 2 Moving Objects * When a fast-moving object hits a slower moving object traveling in the same direction, the slower moving object will accelerate to the speed of the fast-moving object, and the fast- moving object will slow to the speed of the slower moving object. No momentum is lost, except to friction.

27 Momentum of 2 Connected Objects * When a moving object hits and connects with a stopped object, half of its momentum transfers to the other object and they travel together with twice the mass but half the velocity, so total momentum is conserved.

28 September 28, 2012 Click on the yellow boxes to reveal the resulting speeds of the objects. Click on the red lines to reveal the resulting momentum of the objects. Connecting objects. One moving & one stopped object. One fast & one slow object.