Find the degrees a drum must rotate to lift a box 1 foot if the diameter of the pulley on the hoist is 8 inche?
An electric hoist is used to lift a box using a pulley. The diameter of the pulley is 8 in and the box must be raised 1 foot. find the number of degrees through which the drum must rotate to lift the item 1 foot.
3 Responses to “Find the degrees a drum must rotate to lift a box 1 foot if the diameter of the pulley on the hoist is 8 inche?”
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acepimp2 on June 16th, 2013
171.97 degree
Scott R on June 16th, 2013
so the correct way to do this is pretty simple. you use the equation:
s = r * theta
where
s = arc length (linear) ….. in this case one foot
r = radius of the pulley ( r = d/2 = (8in) / 2 = 4 in
theta = the angle you rotate through
solving for theta yields:
theta = s / r
= [1ft*(12in/1ft)] / (4 in)
theta = 3 radians
if you need your answer in degrees, simply multiply by (180/pi)
…… (360 degrees in 2pi radians)
theta = (3 radians) * (180degrees / pi radians)
theta = 171.9 degrees
Irv S on June 16th, 2013
12″ : 8 Pi” = x : 360
do the arithmetic.