1. Review A force is any push or ____________.
Force is measured in the unit _____________
ionsforcesandtime/force/

3. 2 groups of forces CONTACT FORCES Examples: Friction Normal Applies
FORCES ACTING FROM A DISTANCE Examples” Electrical Magnetic Gravity

4. Applied Force
a force that is applied (by contact) to an object by a person or another object Examples) pushing open a door lifting weights throwing a ball moving a box

6. Friction
The force of one object or surface rubbing against another. It opposes motion. STATIC: Stays still KINETIC: Moving (Examples) snowboarding car driving on the road lab table against the floor

7. 2 factors that effect Friction
Surfaces touching
Pressure of objects

8. Effects of friction
Objects slow down
Objects heat up

9. Normal Force
the support force exerted upon an object that is in contact with another stable (still) object Examples) book on a table standing on the ground leaning against the wall

11. Electrical Force
The force of charges (positive and negative) that react with each other -The closer together the particles are, the stronger the force they create Example) lightening in picture above

13. Gravitational Force
The force that pulls objects towards each other Weight is the force of gravity on an object Any object with mass (matter) has gravity= The Law of Universal Gravitation

15. 2 things affect gravity
Mass
Distance between objects

16. Magnetic Force
Magnetic poles attracting or repelling

18. Some other forces:
Tension: force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends

19. Some other forces:
Spring Force: the force exerted by a compressed or stretched spring upon any object that is attached to it

21. When the forces are ______________, they cause an object to speed up, slow down, or change direction.

22. The overall amount of forces acting on an object is a _________ force
The overall amount of forces acting on an object is a _________ force. If the forces are acting in the same way then add them
Boy= 20 N Girl =20N
= 40 N

23. If the forces are opposite, subtract them.