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

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

5. The moon has about a 70% effect on our tides. The sun has a 30% effect
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.

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.

8. Law of Universal Gravitation
All objects in the universe attract each other through the force of gravity.

9. NECAP QUESTION
2009

10. Acceleration of free-falling objects
VELOCITY
1. All falling objects accelerate (change ____________) towards the _________ of the Earth due to __________
CENTER
GRAVITY
the acceleration of a falling object due to gravity (on Earth) =
9.8 m/s2 or 9.8 m/s/s

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

13. 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
Moon = 1.63 m/s/s

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

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
GREATER

16. A flat sheet of paper falls slowly because of air resistance -it reaches its TERMINAL VELOCITY right away.
Weight
Air
Resistance
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…”
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.
Drag
Weight

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

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…

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

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

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