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Unformatted text preview: Work (in Physics) In Physics Work is defined as W = F A d cos c circlecopyrt L.Frommhold . p.21/21 No Work, but (Lots of) Sweat ? A person standing at the bus stop may get tired, but he is doing no Work , W = F A d cos because d = 0 . Even if he were walking home, W = 0 , because of cos = 0 . c circlecopyrt L.Frommhold . p.20/21 Units of Work Work done on an object by a constant force is the product of displacement and the component of the force parallel to the displacement, W = F bardbl d = ( F cos ) d is the angle between force vector F and displacement vector d . Work is measured in units of N m, or Joule (J). Other units are erg and ft lb; 1 Joule = 10 7 erg = 0.7376 ft lb Work is typically done by an agent, or a motor,. . . c circlecopyrt L.Frommhold . p.19/21 Example 61 The net force is given by vector F net = vector F agent + vector F fr + vector F G + vector F N x component: F x , net = F agent cos  F x , fr y component: F y , net = F agent sin  mg + F N Work W = F agent cos x c circlecopyrt L.Frommhold . p.18/21 Mountain Climber A mountain climber does work by lifting his weight to the top of the mountain, vector F agent + vector F G = 0 Note that vector F agent is vertical so that W = F agent d cos = mg h A person (m=100 kg) climbs a mountain (2000 m high) does work W = 100 kg g 2000 m 2 10 6 J c circlecopyrt L.Frommhold . p.17/21 About Energy and its Price...
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This note was uploaded on 10/21/2009 for the course PHYSICS 30 taught by Professor Dr.lotharfrommhold during the Spring '09 term at University of Texas at Austin.
 Spring '09
 Dr.LotharFrommhold
 Physics, Work

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