Ph 111 NAME ____RWBOctober 10, 2008 Quiz 3 SolutionsPlease use the value of 9.8 m/s2for the acceleration of gravity, and give your numerical answers to at least three significant figures. A crate with a mass of m= 10 kg is sliding at a constant speed v1along a frictionless horizontal table, when it encounters a friction patch, with coefficient of kinetic friction μk= 0.4 . After the crate has slid for a distance d= 8 m, its speed is v2= 11 m/s. Histogram, Quiz 30102030Bin012345678910BinFrequencyPh 111.01, Fal l 2008. 110 peopl e; aver age = 5.3/ 10 C or better(a)Find the work done by the normal force over the distance d. The normal force is perpendicular to the displacement - so there is no work done. 0.00 J(b)Find the work done by friction over the distance d. The frictional force is ( )( )( )20.4 10 kg9.8 m/s39.2 NfNmgμμ====The work done is negative, given by -313.6 J()()N 8 m313.6 J=−nc-- 39.2Wfd(c)Find the speed v1of the crate when it first encounters the friction patch.
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This note was uploaded on 05/13/2010 for the course PHYSICS 111 taught by Professor Staff during the Fall '08 term at S.F. State.