Question 295386
The circumference of the circle traced out by the edge of the blade is given by
{{{C=2*pi*R=2*pi*2.75=5.5*pi}}}
It travels this circumference 420 times each minute.
{{{V=5.5*pi*420=2310*pi}}} with units of meters/min.
V=7257 meter/min*(1 min/60 sec)=121 m/s or about 271 mph.