<PRE><B>Question 499660</B>
The horsepower (hp) that a shaft can safely transmit varies jointly with its speed (in revolutions per minute rpm) and the cube of its diameter. If the shaft of a certain material 2 inches in diameter can transmit 36 hp at 75 rpm, what diameter must the shaft have in order to transmit 14 hp at 30 rpm?
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hp = k*rpm*d^3
36 = k*75*8
k = 36/600 = 0.06
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14 = 0.06*30*d^3 = 1.8d^3
d^3 = 14/1.8
d =~ 1.981 inches

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