Question 1004806
The circumference is:
{{{ C = pi*d }}}
{{{ d = 7.5 }}} in
{{{ C = 7.5*pi }}}
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This is like a problem where string is
wrapped around the cicumference and
is unwound at a certain speed. How many 
feet of string unwinds in one second?
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{{{ 7.5*pi*2400 }}} inches of sawblade
passes by the wood in one minute
{{{ 18000*pi }}} in/min
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[ ft/sec ] = [ in/min ] x [ ft/in ] x [ min/sec ]
{{{ 18000*pi*( 1/12 )*( 1/60 ) }}}
{{{ 25*pi = 78.54 }}} ft/sec
Hope I got it