1. Warm-Up October 26, 2015 “Super Sliders” and other similar products claim to allow you to “effortlessly slide heavy furniture.” How do they work?

2. Free Body Diagram Answers

3. Force Situations Worksheet

4. Friction Section 5.2

5. Two Types of Friction Kinetic Friction: When an object is moving Static Friction: When an object is not moving (stationary) (There are other types of friction that we will not discuss in this course.)

6. Kinetic Friction

7. Kinetic Friction Force

8. Example 1

9. You-Try #1 You are pushing a 25.0 kg box horizontally with a force of 125 N. The coefficient of kinetic friction is 0.35. a) What is the force of friction? b) What is the resulting acceleration?

11. Warm-Up: October 27, 2015

12. Static Friction

13. Static Friction Force

14. Example 2 A 30.0 kg box is at rest on the floor. If the coefficient of static friction is 0.55, what is the maximum push force you could apply to the box before it starts moving?

16. You-Try #2 A 15.0 kg box is at rest on the floor. If you have to push with a force of 95 N before the box starts to move, what is the coefficient of static friction?

18. Warm-Up: A 70.0 kg couch is at rest on the floor. If the coefficient of static friction is 0.65, what is the maximum push force you could apply to the couch before it starts moving? (Look at example 2 if you don’t remember how to solve this)

19. Friction Coefficients For a given surface combination, the coefficient of static friction will always be larger than the coefficient of kinetic friction. It’s harder to get something to start moving than to keep it moving.

20. Assignments: Read Section 5.2 of your textbook (pages 126-130) Page 128 #17-20 Page 130 #27, 28, 30 Braddock House Clean-Up Worksheet ◦ On website

21. Worksheet “Braddock House Clean-Up”

23. Warm-Up: October 28, 2015 A box is pushed along a horizontal floor giving the box a speed of 3.2 m/s. 1.7 seconds after the end of the push, the box stops. What is the coefficient of kinetic friction between the box and the floor?

25. Force Situations

26. October 28, 2015 Read Section 5.2 of your textbook (pages 126-130) Page 128 #17-20 Page 130 #27, 28, 30 Braddock House Clean-Up Worksheet ◦ On website Read Section 5.3 of your textbook