1. Forces THEY KEEP US GROUNDED

2. What is force?  A force is simply a push or a pull.  F = ma (mass x acceleration)  Forces are measured in Newtons  Force has direction (whichever way it is being pushed or pulled)

3.  Forces in the same direction can add to make a greater force. 5 N = 10 N Two forces can be added to produce a greater net force in the same direction. Net Force 5 N15 N = 10 N Two forces can be added to produce a greater net force in the same direction.

4. Net Force  Forces in opposite directions will subtract to make lesser force.

5. Balanced Forces  If forces going in opposite directions are equal, they are balanced and no movement happens

6. Unbalanced Forces  If two forces are pushing in the same direction, movement happens in that direction.

7. Unbalanced Forces  If unequal forces are moving in the opposite direction, movement happens in the direction of the greater force.

8. Types of Forces  In nature the two main types of forces we will talk about are:  Electric and Magnetic  Gravitational

9. Gravitation  Gravity - The pull to the center of an object with mass. Interesting fact: The force of gravity from Earth on the moon is equal to the force of gravity from the moon on Earth.

10. Gravitation  Scientists do not know what causes gravity.  However, they know a lot about it.  Larger masses have a larger gravitational force.  Example: If Earth had twice as much mass and the same volume you would weigh twice as much.  Example: If Earth had half as much mass and the same volume you would weigh half as much.

11. Mass of Earth m = 6 Yg (Yottagrams) Mass of 2xEarth m = 12 Yg (Yottagrams) 440 lb 2000 N 220 lb 1000 N

12. Gravitation  The closer the object, the more the force of gravity.  Example: If you built a tower 6,371 km high you would weigh ¼ of your weight because you’re twice the distance from the center of the Earth.  Example: If Earth’s radius was halved, but maintained the same mass you would weigh 4 times as much.

13. Earth’s radius r = 6,371 km 220 lb 1000 N 2xEarth’s radius r = 12,742 km 55 lb 250 N

14. Electric and Magnetic  A force that is created by charged (- or +) particles.  Remember that opposites charges attract!  Same charge repel!