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Unformatted text preview: Physics 140 – Fall 2007 lecture 7 : 25 Sep Notices: • first midterm exam Thursday, 4 Oct, 6:007:30 pm • Review next TUESDAY evening (8pm, 182 Dennison) • discussion section reviews on Wed, 3 Oct • need alternate time? Explain your situation in an *** email to: [email protected] *** • practice exam posted to CTools (under Exams & Grading) Ch 5 topics: • friction • circular motion dynamics HW Set 1 HW Set 2 total score score per problem time per problem HW Set 3 (as of Mon, 6pm) Note: closes in 1 day, 6 hours! Two identical masses are attached to either end of a very light rope draped across the very light pulley as shown. If angle A is a right angle, then the acceleration of the righthand block in the idirection, expressed in terms of the tilt angle ! , is 1. 2 g cos ! 2. ( g/2 ) sin ! 3. 2 g (cos ! – sin ! ) 4. ( g/2 ) (sin ! + cos ! ) 5. ( g/2 ) (cos ! – sin ! ) ! A i Frictional Forces At the contact surface between , the component of force directed parallel to the surface is known as friction . Static friction acts to keep an object at rest (static) against its contact surface. It can take on any magnitude up to a maximum value f s < f s MAX = μ s n where n is the normal force acting on the object at the surface....
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 Fall '07
 Evrard
 Circular Motion, Force, Friction, Captain Kittinger

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