PHY 1420 Midterm: Test 2 Notes
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Chapter 5: using newton"s laws: friction, circular motion, drag forces. Static friction applies when two surfaces are at rest with respect to each other (such as a book sitting on a table) Usually it is easier to keep an object sliding than it is to get it started. Uniform circular motion: motion in a circle of constant radius at constant speed. Instantaneous velocity is always tangent to the circle. However don"t have constant velocity since direction is changing all the time. Therefore acceleration is not zero. (since velocity is changing) Magnitude of acceleration is always constant, though, just the direction. If you spin a lanyard and while spinning cut the lanyard, it will fly away. Therefore, there is tension force acting on it. To find minimal velocity to keep lanyard spinning, find minimal force of tension. Direction of acceleration points to the center of the circle of spin. When you hear of a circle, always think of (cid:1832)=(cid:3118)(cid:3045)
