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## Homework Statement

The Hubble Space Telescope is stabilized to within an angle of about 2 millionths of a degree by means of a series of gyroscopes that spin at 1.92×104 . Although the structure of these gyroscopes is actually quite complex, we can model each of the gyroscopes as a thin-walled cylinder of mass 2.00 and diameter 5.00 , spinning about its central axis.

How large a torque would it take to cause these gyroscopes to precess through an angle of 1.30×10−6 degree during a 5.00 hour exposure of a galaxy?

## Homework Equations

L=I*ω

torque = Ω*L

I=mr^2

Ω=Δθ/Δt

## The Attempt at a Solution

ω=1.92*10^4rpm

=2010.62rad/s

I=mr^2

=2(0.005)^2

=0.005

Δθ=1.3*10^6deg

=7.4484*10^-5rad

Δt=5 hours

=18000s

torque = Ω*I*ω

=(7.4484*10^-5/18000)*0.005*2010.62

=4.1*10^-8 Nm

This is the wrong answer and I feel as if the torque shold be rather larger by intuition. Any help would be appreciated.

Edit: 3.17*10^-12 Nm turned out to be the correct answer, but i'd still like to know how to do this question.

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