Calculating Friction with Free-Body Diagrams
Learning Objective
I can draw a free-body diagram and use it to calculate the coefficient of friction.
Key Concepts
Kinetic friction slows objects down as they slide, while static friction must be overcome to start an object's movement.
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.
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.
Practice Questions
This lesson includes 12 practice questions to reinforce learning.
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1. What is the primary difference between static and kinetic friction?
2. Explain how the normal force affects friction.
3. A box rests on a horizontal surface. You push it with a force of 50 N, but it doesn't move. What is the magnitude of the static friction acting on the box?
...and 9 more questions
Educational Video
Friction: Crash Course Physics #6
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