1. Gravity & Motion Unit 1 Lesson 4
Big Idea: Unbalanced forces cause changes in the motion of objects, and these changes can be predicted and described
Essential Question: How do objects move under the influence of gravity?

2. What is Gravity?
Gravity is a noncontact force of attraction between objects due to their mass.
All objects on Earth fall at the same rate once air resistance and other factors are removed.
Force = mass × acceleration due to gravity (F = mg), where g is about 9.8 m/s2.

3. There must be no air resistance

4. What is Gravity? 3,400km = 2113 miles 6371.39km = 3959 miles
All matter has mass, so all matter is affected by gravity
All objects experience gravitational attraction to all other objects
Earth and other planets are round because of gravity
3,400km = 2113 miles
km = 3959 miles

5. What is Gravity? 15km = 9.32 miles
Some objects in space are not round because they are too small for gravity to shape them into a sphere
The paths of the planets, the sun, and our galaxy are determined by gravity
15km = 9.32 miles

7. What Determines the Force of Gravity?
The law of universal gravitation states that all objects attract each other through gravitational force
The strength of the gravitational force is related to the mass of the objects and the distance between them

8. What Determines the Force of Gravity?
Gravitational force between two objects increases as the distance between their centers decreases
Gravitational force between two objects increases as their masses increase
Objects with greater mass have more attraction between them than objects with smaller mass have between them

9. Gravitational force decreases as distance increases
Gravitational force increases as mass increases

10. Jupiter
Earth
Venus
Mars

11. How Does Gravity Keep Objects in Orbit?
Free Fall is when gravity is pulling an object down and no other forces are acting on it
An object is in orbit when it travels around another object in space
Forward motion and free-fall motion combine to cause orbiting

12. When gravity is the only force acting upon it, an object is in free fall

13. How Does Gravity Keep Objects in Motion?
Spacecraft, satellites, the moon, planets, and stars all complete orbits
Any object in curved motion is constantly changing direction
Gravity pulls objects toward the center of an orbital path

14. The object would fly off into space along a straight line

15. How Does Gravity Keep Objects in Orbit?
Describe how forces keep the moon in orbit around the Earth