A wheel has eight spokes and a radius of 38.0 cm. It is mounted on a fixed axle and is spinning at 2.80 rev/s. You want to shoot a 27.0 cm long arrow through the wheel, parallel to this axle, without hitting any of the spokes. Assume that the arrow and the spokes are very thin and evenly spaced. What minimum speed must the arrow have?(adsbygoogle = window.adsbygoogle || []).push({});

Ok.. This is how I tackled it:

First I converted 2.8 rev/s to rad/s using the equation 1 rev = 2*pi rad and got 17.593 rad/s

Then for the distance of a section of the wheel between the spokes I used the equation s = R*angle where R is the radius, so:

s = (0.38 m)((2*pi rad)/8) = 0.298 rad*m

Then I wasnt sure what I could do to get the minimum speed but I figured I'd find how long it'd take for s to "go by" using the angular velocity.. so I divided s by 17.593 and got 0.0170 seconds.. then I divided the length of the arrow (0.27 m) by 0.0170 seconds and got 15.88 m/s

Apparently that's not the answer. Anyone know whats up ?

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# Rotational Kinematics Problem

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