How fast would a rotating fan be spnning to slice a 1 cm long bullet into 10 pieces.?

Question

The fan is 2 meters in diameter, it has 4 blades. The centerpiece is half a meter wide.

How fast would the fan have to be spinning to slice a 200 mph bullet into 10 pices.

Answer 1

speed of bullet=200mph
=200*1.609343 km/h
=321.8686 km/h
=321,868.6 m/h
=32,186,860cm/h
the bullet has to be cut every
1/10 th cm
number of cuts/hour required
=321,868,600
the fan has four blades,therefore,
the fan cuts four times per rev
number of revs/hour required
=321,868,600/4
but,there are 3600 secs in an hour
number of revs/secs required
=321,868,600/(4*3600)
=22,351.98611

therefore,the blades of the fan have
to make 22,352 revs/second
in order to cut the cm long bullet
into 10 pieces

i hope that this helps

Answer 2

Damn nuisance that you give some of the dimensions in metric and some in English units.

Be thankful that the number of blades and the number of "pices" don't have units.

The diameter of the fan is irrelevant. We want the leading edge of each blade to arrive at the point of its predecessor after the bullet has traveled 1/10 of a cm.

How long does it take for a 200mph object to travel 1/10 of a cm?

t = (1 / 10) cm * (1 / 200) hours / mile * 3600 seconds / hour * 1 / 5280 mile / feet * 1 / 12 foot / inches * 1 / 2.54 inch / cm

That should do it for t in seconds.

The fan must rotate 1/4 of the way in t seconds, or once around in 4t seconds. The rotational speed is 1/4t revolutions per second.