3. GRAVITY

7. The acceleration due to gravity on Earth is 9.8 m/sec 2 (~22 mph/sec) (This means that each second an object falls, it increases its speed by 9.8 m/sec until it reaches its terminal velocity) a force of acceleration that causes objects to become attracted to each other -based on the object’s mass and distance between them

8. Gravity pulls all objects at the same rate. Mass does not affect the pull from gravity. Weight: How heavy an object is because of gravitational pull Mass: Amount of matter in an object

9. However…. Some objects do fall slower because of AIR RESISTANCE -A force that opposes the motion of an object as it moves through air

10. highest speed that an object can fall at determined by the object’s shape and mass Once an object reaches its terminal velocity, it falls at a constant velocity. (It does not accelerate unless its shape changes.) TERMINAL VELOCITY Some objects also fall slower because of their…… Reaches this when the air resistance exerts an upward force exactly equal and opposite to the force of gravity. Heavier mass needs faster falling speed for drag to equal gravity

11. The elephant hits first because of its mass. It takes more time to reach its terminal velocity. The feather reaches its terminal velocity very quickly because it has very little mass.

12. Vacuum: A vacuum is a place that has no matter – thus there is no air (ex: in outer space) All objects will fall at the same velocity regardless of shape and mass. If there is no air, there is no air resistance

13. Tennis ball test …..but with air resistance and outside factors, the speed should be between 40-50 mph. A tennis ball’s terminal velocity is about 70 mph. Other Terminal Velocities Human ~120mph Raindrop ~ 12mph 16lb Bowling Ball ~ 163mph Baseball ~ 75mph

14. HOW WOULD OUR LIVES BE DIFFERENT WITHOUT GRAVITY???

17. http://www.explorelearning.com/ Sign up for the gravity interactive – off the leaning tower of pisa Teacherdomain.org

18. Balloon Car Project due Friday Poster Data Tables (re-done on the computer) Distance Top Speed Momentum Builders Journal (preferred typed) Terms Sheet (typed)

19. UPCOMING SCIENCE EVENTS Mini Project Next Week Test on Thursday 22 nd 1 st or 2 nd Week in January Science Placement Test from PV

20. LET’S REVIEW………..NEWTON’S LAWS

21. AN OBJECT IN MOTION WILL STAY IN MOTION UNLESS ANOTHER FORCE STOPS IT AN OBJECT AT REST WILL STAY AT REST UNLESS ANOTHER FORCE STARTS IT FIRST LAW

22. SECOND LAW FORCE = MASS x ACCELERATION “HEAVIER OBJECTS NEED MORE FORCE TO GET THEM GOING OR TO STOP THEM”

23. THIRD LAW EVERY ACTION HAS AN EQUAL AND OPPOSITE REACTION AIR GOES THIS WAY CAR GOES THIS WAY

24. IT WILL NOT MOVE UNTIL YOU GIVE IT A FORCE-IT WON’T STOP UNTIL FRICTION OR A WALL STOPS IT. YOUR BALLOON CAR WILL EXPERIENCE ALL THREE THE HEAVIER YOUR CAR IS, THE MORE FORCE IT WILL TAKE TO GET IT GOING WHEN THE AIR COMES OUT OF THE BALLOON, YOUR CAR WILL GO FORWARD (the opposite way)

25. WHY DO THINGS FALL??