1. GRAVITY: Ch 12. Sec. 2 pages 403-410 GRAVITY IS EVERYWHERE!

2. A. GRAVITY = The FORCE of ATTRACTION between ANY two objects  All matter (anything that has mass) has gravity…but it’s only noticeable between massive objects (like planets…)

3. The size of this gravitational force depends on 2 factors: 1. __________________________ Mass of the objects *As mass increases, the force of gravity increases Ex: Earth vs. moon

4. This is why we’re “stuck” to the surface of the Earth instead of being pulled off towards the more- massive sun. 2. _________________________________ Distance between the objects *As distance between the two objects _________, the force of gravity _________. increases decreases

5. The moon has about a 70% effect on our tides. The sun has a 30% effect. The sun’s gravity is stronger (179x stronger than the moon), but it’s far away. Spring tides: action of tides springing out and back. (highest highs and lowest lows) Neap tides: Sun and moon are at right angles to one another and tidal influences partially cancel each other out. (difference between high tide and low tide is minimal)

7. The rotation (spinning) of the Earth creates the equatorial “ bulge ” The Earth ’ s diameter at the equator is 27 miles more than the pole to pole diameter So at the poles you are closer to the center of the Earth, so you weigh slightly more. Poles @ sea level: 9.780 m/s 2 Equator @ sea level: 9.832 m/s 2  ~0.5% more force

8. Law of Universal Gravitation All objects in the universe attract each other through the force of gravity. As distance increases, force decreases. As mass increases, force increases.

9. NECAP QUESTION 2009

10. B. Acceleration of free- falling objects 1. All falling objects accelerate (change ____________) towards the _________ of the Earth due to __________ the acceleration of a falling object due to gravity (on Earth) = 9.8 m/s 2 or 9.8 m/s/s VELOCITY CENTERGRAVITY

11. But…on Earth, not all falling objects hit the ground at the same time because of _____________ or _______________. air resistance FLUID FRICTION This means that the velocity of a freely-falling object __________ by ____ m/s for every _______ that passes (up to a certain point…) INCREASES 9.8 SECOND

13. Force of G on Moon = 1.63 m/s/s On the moon…all objects hit the surface at the SAME time because there is no ____ on the moon. There IS GRAVITY. Gravity = ____ of Earth. AIR 1/6 Hammer & Feather Drop on Moon (Apollo 15) Water Balloon Fight in Space

14. C. Terminal Velocity The __________ speed that an object can have in freefall due to ___________________. MAXIMUM AIR RESISTANCE -shape -size -weight Terminal velocity changes depending on the object’s

15. As objects fall, _____________ increases until it balances the _______ of the object FLUID FRICTION WEIGHT Therefore, a heavier object will accelerate for a _________ time period and have a __________ terminal velocity. GREATER Flying Squirrel Suits?!

16. Air Resistance Weight A flat sheet of paper falls slowly because of air resistance -it reaches its TERMINAL VELOCITY right away. If placed on a magazine, the paper accelerates with the magazine. Since the magazine weighs more, it accelerates for a longer time period.

17. “DROPPED FROM A HIGH POINT…” Drag Weight Golf Ball Ping pong Ball -A ping pong ball reaches its terminal velocity first -A golf ball continues to accelerate for a greater time period and has a greater terminal velocity- so it hits the ground first. -Falling Objects Lab!

18. FALLING PENNIES

19. FALLING CATS -There are cats on record that have survived falls of over 32 stories (~320 feet). -They are more likely to die in falls less than 5 stories. HOW IS THIS POSSIBLE? -On average, cats reach their terminal velocity (60 mph) after falling about 5 stories. - Once reaching this velocity, they relax and spread out like a parachute, minimizing injuries.

20. D. Projectile Motion: The two motions DO NOT affect each other Motion that has two components (horizontal & vertical) that combine to form a __________ path CURVED

24. Astronauts “float” when inside an orbiting spaceship because they are _______________! in FREE FALL

25. PARABOLIC FLIGHTS…experience “weightlessness” as you free fall with a plane….. only $2,950 per person!

26. ZERO GRAVITY CLASSROOM… Zero Gravity!

27. E. Weight vs. Mass 1. MASS The amount of _________ in an object that _______ changes. Measured in ___ 2. WEIGHT The gravitational ________ that an object experiences because of its _______. Varies (changes) by location MATTER NEVER FORCE MASS kg

28. Weight is a FORCE. F = ______________ Mass= 60kg mass x acceleration

29. Homework: KIM vocabulary strategy using the following terms:  weight  mass  free fall  terminal velocity  projectile motion KIM vocabulary strategy using the following terms:  weight  mass  free fall  terminal velocity  projectile motion