What is Friction ( contact force )

1.  What is Friction ( contact force ) Force that acts when two objects rub (contact) each other Friction comes from solid, air or water http://phet.colorado.edu/sims/friction/friction_en.html ( Let us visit this website) 

2. How does Friction affects motion? Friction opposes movement

3. How does Friction affects motion? Slows down

4. How does Friction affects motion? Getting moving

5. How does Friction affects motion? Getting moving

6. How does Friction affects motion? Grip or stop

7. Factors affecting friction ( surface)http://www.bbc.co.uk/schools/scienceclips/ages/8_9/friction.shtml ( visit this website) Smooth surface Rough surface Lesser bump and hollows means lesser friction can move the object continuously with little force. More bump and hollows means more friction Can move the object slowly with greater force

8. Smooth surface The smoother the surface the faster the object glides with little force

9. Rough surface Objects will move slowly with greater force on the rough surface.

10. Factors affecting friction Air Resistance Example: Is the force that provide a backward force Size and shape are the factors that affect air resistance. ( the bigger the size and shape the more is the air resistance) http://www.youtube.com/watch?v=oTMLXBeQ40E http://www.youtube.com/watch?NR=1&v=ur40O6nQHsw

11. Friction: Good and Bad Good Bad Hold objects Stops object Able to play ,run ,walk etc Gives energy Shoes, slippers , tires and anything that are used for moving are worn out. Machine become less efficient Reduce speed Cause accidents Cause sparks

12. Ways of reducing friction Applying wax or polishing Use rotating objects Streamlining New design shoes for the athletes