Ch+4+Sec+4

The more gravity a roller coaster has the faster you go
 * What do you see?**

Gravity has a direction to the Earth's crust. Australia can be held on Earth because they are being pushed towards the core.
 * What do you think?**


 * Physics Talk**
 * Earth's gravitational Field
 * Gravitational field: the gravitational influence in the space around a massive object
 * needs a source of the field and a second object to interact with the field, the response object
 * Gravitational field lines show
 * direction of the gravitational field
 * that the field is stronger where the lines are close together and weaker where the lines are further apart
 * some points of the field
 * that the field extends to infinity
 * Inverse-Square Relationship
 * inverse-square relationship; the relationship between the magnitude of a gravitational foe and the distance from the mass
 * it also describes how electrostatic forces depend on the distance from an electrical charge
 * Newton's law of universal gravitation: all bodies with mass attract all other bodies with mass
 * the force is proportional to the product of the two masses and gets stronger as either mass gets larger
 * gravity: force of attraction between two bodies due to their masses
 * Universal Gravitation equation
 * [[image:Screen_shot_2011-03-21_at_5.16.13_PM.png]]
 * Fg= force between bodies
 * r= distance between their centers
 * m1 and m2= the masses of the bodies
 * G= universal constant that = 6.67x10 -11 N*m^2/kg^2

Physics Plus

Checking up 1. The direction of the strongest gravitational field is to the center of the earth. 2. The closer you are to an object, the stronger the field. 3. You divide it by 9 4. Gravity 5. Circular

Physics Plus 1 Given in book 2

3

4 They are similar

1 1 year=31536000 seconds

2

PTG 1. 250N

2.

3. We have always believed in it and there is no reason not to

4. They are equal

5. a) The water on the side of the earth facing the moon b) The gravity of the moon and the earth is too weak to effect the entire planet, only the water is effected c) The force of gravity is stronger when the moon and the water get closer

6. a) They wouldn't be able to survive, there wouldn't be a body of water for them to live in b) yes, without gravity water wouldn't be pushed down

7. a) divided by 4 b) divided by 9 c) divided by 16 d) multiplied by 4

8

a) divided by 4 b) divided by 9 c) divided by 16 d) multiplied by 4

9 a) doubled b) tripled c) quadrupled d) halved

10 a) double b) 9X c) 6X


 * What do you think now?**

Gravity is always pointing to the earth's center. People all around the world are held on because they are being pushed towards the center of the earth.