2. Velocity = 2 mi/hr What is the Net Force? 50 lbs ZERO! THERE IS NO ACCELERATION FfFf

3. FRICTION Weight What direction does the FORCE of FRICTION act? Normal Force

4. Force of Friction = μ · Normal Force F f = μ · F N FRICTION Weight μ is the coefficient of friction! Normal Force

5. Force of Friction Normal Force Coefficient of Friction Glass on Glass (1.0) Brake Material on Iron (0.4) Swiss Wax on Dry Snow (.03)

6. http://www.drivingcamp.it/FOTO/Neve02.jpg F f = μ · F N FfFf Car

7. F f = μ · F N Increase Normal Force… Increases the Friction Force!

8. http://www.alpinelimo.com/tire.jpg F f = μ · F N Increase μ … Increases F f …

9. http://www.jmevans.fsnet.co.uk/DriveChallenge/Skid_car.jpg F f = μ · F N Decrease Normal Force…Decreases Force of Friction!!!

10. http://www.imoc.co.uk/news/img/skid-10.jpg F f = μ · F N Decrease μ … Decrease Force of Friction!!!

11. http://users.bigpond.net.au/pb/Sonja.jpg F f = μ · F N How can a climber just stand there like that without using their arms?

13. FwFw FxFx FyFy The normal force [F N ] is always perpendicular to the surface it acts on! FNFN

14. FwFw FxFx FyFy FNFN

15. Force of Friction Pull on String Static Friction Kinetic Friction Break Free of Static Friction Dynamics of Friction

16. Friction Pull μ static > μ kinetic

17. http://mirrorimageorigin.collegepublisher.com/media/paper299/stills/91lgzfkc.jpeg

18. http://www.yorkvillagefire.com/mva121203b.jpg

20. http://www.ecy.wa.gov/programs/air/images/Emisch1.jpg

21. Air Resistance is a function of Cross Sectional Surface Area and Velocity

22. http://superunleaded.org/img/freeway.jpg

23. Weight Air Resistance Net Force Weight Air Resistance Net Force

24. Weight Air Resistance Net Force = ZERO Acceleration = ZERO Velocity is CONSTANT TERMINAL VELOCITY What is TERMINAL VELOCITY?