1. GRAVITY AND NEWTON’S LAWS OF MOTION

2. Question???? Which object will land sooner if dropped at the same time, a tennis ball or a bowling ball ?

3. Acceleration Due To Gravity Objects fall to the ground at the same rate because the acceleration due to gravity is the same for all objects. The mass of an object does not affect the rate at which it falls. Example of acceleration due to gravity http://www.regentsprep.org/Regents/physics/phys01/accgravi/index.htm Bowling ball and tennis ball

4. ACCELERATING AT A CONSTANT RATE All objects accelerate toward Earth at a rate of 9.8 m/s/s. WHAT DOES THIS MEAN? This means that for every second an object falls, the object’s downward velocity increases by 9.8 m/s.

5. Acceleration Due To Gravity Objects fall to the ground at the same rate because the acceleration due to gravity is the same for all objects. The mass of an object does not affect the rate at which it falls. All objects accelerate toward Earth at a rate of 9.8 m/s/s.

6. What happens when I drop a tennis ball and a piece of paper?? Is there something else acting on the paper to cause it to not fall like the tennis ball? What?

7. DOES AIR RESISTANCE AFFECT FALLING OBJECTS? Yes!! THE FORCE OF GRAVITY PULLS OBJECTS DOWNWARD AS THE FORCE OF AIR RESISTANCE PUSHES IT UPWARD. FREE FALL- when an object is being pulled down by gravity, but no other forces are acting on it. Does free fall occur with air resistance?

8. http://www.youtube.com/watch?v=5C5_ dOEyAfk Example of acceleration due to gravity

9. Gravity, Free Fall, and Air Resistance Gravity - the force that pulls objects toward one another. Free Fall – when only gravity is acting on an object. This is rare because of air resistance. All objects free fall at a rate of 9.8 m/s. A golf ball and basketball will hit the ground at the same time. Air Resistance – type of fluid friction which increases with the surfacearea of the object.

11. Newton’s Laws of Motion Brainpop

12. NEWTON’S FIRST LAW OF MOTION AKA: LAW OF INERTIA An object at rest remains at rest and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force. A golf ball on a tee. The man will remain in motion until a force stops his movement. Examples:

13. NEWTON’S FIRST LAW OF MOTION Also called: LAW OF INERTIA Inertia is the tendency of all objects to resist any change in motion.

15. NEWTON’S SECOND LAW OF MOTION The acceleration of an object depends on the mass of the object and amount of force applied. FORCE=MASS X ACCELERATION Or a=F/m How does Newton’s Second Law explain why the shuttle’s acceleration increases during takeoff?

17. The greater mass or velocity an object has, the greater its inertia. You can test this the next time you're at the grocery store! It takes a strong push to get a loaded shopping cart moving, but once it gathers speed it keeps going, even if you let go of the handle. When you stop a moving cart full of groceries, it takes much more force to stop it than an empty cart. Why? (it has more mass).

18. WHAT IS MOMENTUM? MOMENTUM is a property of a moving object that depends on the object’s mass and velocity. THE MORE MOMENTUM AN OBJECT HAS, THE HARDER IT IS TO STOP THE OBJECT OR CHANGE ITS DIRECTION. Momentum=mass x velocity

19. NEWTON’S THIRD LAW OF MOTION For every action there is an equal and opposite reaction. FORCES ALWAYS ACT IN PAIRS. The action force is the swimmer’s hand and feet pushing the water. The reaction force is the water pushing on the swimmer’s hands and feet.

20. According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body.

21. Flying gracefully through the air, birds depend on Newton’s third law of motion. As the birds push down on the air with their wings, the air pushes their wings up and gives them lift.Flying gracefully through the air, birds depend on Newton’s third law of motion. As the birds push down on the air with their wings, the air pushes their wings up and gives them lift.

22. MORE EXAMPLES OF ACTION AND REACTION FORCE PAIRS The rabbit’s legs exert a force on Earth. Earth exerts an equal force on the rabbit’s legs, causing the rabbit to accelerate upward. The shuttle’s thrusters push the exhaust gases downward as the gases push the shuttle upward with an equal force.

24. LET’S PRACTICE

25. Explain Newton’s First Law of Motion using this picture. A plane will not soar in the air unless it is pushed by the exhaust from its jet engines.

26. Newton’s Second Law of Motion - Which would you have to apply a greater force to stop and go? - Which would you rather buy gas for? -Which would you rather be driving in a head-on collision?

27. NEWTON’S THIRD LAW OF MOTION LIST and DESCRIBE the action and reaction forces in the following picture.