Calculating Friction with Free-Body Diagrams
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Objective
I can draw a free-body diagram and use it to calculate the coefficient of friction.
Part 1 of 4
Warm-up video
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We don't generate video — this one is by CrashCourse on YouTube. The practice questions and exit ticket below were drafted by AI for this objective, and every question is editable in the teacher guide.
Part 2 of 4
Key concepts
3 concepts
- 1
Kinetic friction slows objects down as they slide, while static friction must be overcome to start an object's movement.
- 2
The force of kinetic friction depends on the coefficient of kinetic friction (μₖ) and the normal force (F_N), and is calculated as F_friction = μₖ * F_N.
- 3
When an object is on a ramp, the normal force is equal to (mg) x (the cosine of the angle), where mg is the weight of the object.
Part 3 of 4
Practice
12 questions
What is the primary difference between static and kinetic friction?
Explain how the normal force affects friction.
Part 4 of 4
Exit ticket
Quick comprehension check
“A 10 kg box is placed on a horizontal surface. A force of 49 N is required to start the box moving. Draw a free-body diagram of the box, labeling all forces. Then, calculate the coefficient of static friction (μₛ) between the box and the surface. Show your work.”
Sample answer included in the free materials
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