#Goals: SWBAT...
1. Describe which friction coefficient refers to moving objects, and which refers to objects at rest
2. Draw accurate FBD's
3. Solve problems involving kinetic and static friction
Warm-Up (5min)
Copy and answer the following:
CLASSWORK
1. #034A: Understanding the Force of Friction Equation
Take notes: EDpuzzle
Answer the following:
CH 5 #27: You've now learned about static and kinetic friction. How are these two types of friction similar? What are the differences between static and kinetic friction?
2. #034B: An Example of how to solve a Friction Problem, plus two Practice Problems
A. Copy the following: Example Problem: You apply a horizontal force of 2.0 Newtons to a book with a mass of 0.674 kg, and it begins to accelerate. The values for the coefficients of friction between the book and the incline are µs = 0.27 and µk = 0.24. What is the acceleration of the book?
Take notes as we solve
B. Solve these two on your own:
CH 5 pg 128 Practice Problem #3: You push a 25.0-kg wooden box across a wooden floor at a constant speed of 1.0 m/s. Draw a FBD. How much force do you exert on the box? FYI: for wood on wood, µs = 0.50 and µk = 0.20
CH 5 pg 128 #17: A girl exerts a 36-N horizontal force as she pulls a 52-N sled across a cement sidewalk at constant speed. Draw a FBD. What is the coefficient of kinetic friction between the sidewalk and the metal sled runners? Ignore air resistance.
At Home Learning (HW)
1. Complete the problems from #034B
If you're stuck on Practice Problem #3, or want to check your work, the solution is in CH 5, pg 128. Use the link to the online textbook in the margin to the left.
2. #034C: Period 1-3: Watch/take notes on the following. If you're in period 4-5, scroll down a bit...
Understanding the Force of Friction Equation - EDpuzzle
#034C: For period 5-6: Watch/take notes/complete edPuzzle on the following:
Introduction to Static and Kinetic Friction by Bobby - EDpuzzle
3. #034D: Watch/take notes/complete edPuzzle on the following:
Do Anti-lock Brakes use Static or Kinetic Friction? by Billy - EDpuzzle
Optional Review: Still confused about how to solve problems like these? Try watching the videos below.
Coefficient of Friction
Notes: LINK
A. Are the coefficients for static and kinetic friction the same, or different?
B. Is one always larger than than the other? Which one?
Summing the Forces
Does the Book Move? An Introductory Friction Problem - EDpuzzle