SOLUTION: A pulley with a radius of 9 inches is to be used to lift a box from the ground to a platform. The rope being used has an entire length of 42 feet. If the box needs to be raised 1

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A pulley with a radius of 9 inches is to be used to lift a box from the ground to a platform. The rope being used has an entire length of 42 feet. If the box needs to be raised 1      Log On


   

Question 35603: A pulley with a radius of 9 inches is to be used to lift a box from the ground to a platform. The rope being used has an entire length of 42 feet. If the box needs to be raised 12 feet, how many revolutions will the pulley make? How many radians is that?
Answer by venugopalramana(3286) About Me  (Show Source):
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A pulley with a radius of 9 inches is to be used to lift a box from the ground to a platform. The rope being used has an entire length of 42 feet. If the box needs to be raised 12 feet, how many revolutions will the pulley make? How many radians is that?
PER REVOLUTION THE ROPE TTRAVELS BY ONE CIRCUMFERENCE OF THE PULLEY=2PI*9/12 FEET
IT HAS TO RAISE BY 12 FEET..
HENCE NUMBER OF REVOLUTIONS NEEDED = 12/(2PI*9/12)=12*12/18PI=8/PI=2.55 OR NEARLY 3 REVOLUTIONS.
IT AMOUNTS TO (8/PI)*2PI=16 RADIANS