Question 1141267
Use a constant factor, {{{ k }}}
Let {{{ H }}} = horsepower
Let {{{ s }}} = speed in rpm
Let {{{ d }}} = diameter in inches
{{{ H = k*s*d^3 }}}
{{{ 36 = k*75*2^3 }}}
{{{ 36 = 600k }}}
{{{ k = .06 }}}
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{{{ 73 = .06*45*d^3 }}}
{{{ 73 = 2.7*d^3 }}}
{{{ d^3 = 27.037 }}}
{{{ d = 3.00136 }}} in
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check the math & get a 2nd opinion if needed