Unformatted text preview: W done by the force F ( x ) in moving a particle from a to b to be Z b a F ( x ) dx . Problem. An electric elevator with a motor at the top has a multistrand cable weighing 2 kg/m. When the car is at the ﬁrst ﬂoor, then 60 meters of cable are paid out. When the car is at the top ﬂoor, then effectively meters are paid out. a) What is the force exerted by the motor to just lift the cable? Hint: Newton’s second law says that the force is equal to mass times acceleration, F = ma , with units measured in Newtons [N=kg · m/s 2 ]. You may take the free gravitational acceleration to be g = 10m/s 2 . b) How much work does the motor do just lifting the cable when it takes the car from the ﬁrst ﬂoor to the top?...
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 '07
 BERMAN
 Calculus, Force, Euclidean geometry, Line segment

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