I already posted this somewhere, but silly me, i can't find it.(adsbygoogle = window.adsbygoogle || []).push({});

Q: A disk of radius 2.40 cm and mass 1 kg is pulled by a string wrapped around its circumference with a constant force of 0.36 newtons. What is the angular velocity of the disk to three decimal places after it has been turned through 0.85 of a revolution?

So I started by obtaining my degrees from the 0.85 revolutions (S=rθ). This equals 2.225 degrees.

Next I used ∆x=R∆θ

(2.40)*(2.225)

=5.340 radians

W=F∆x

(0.36)*(5.340)

=1.9224

Using conservation of work (W=∆K):

K=.5Iω^2 (where I of a disk=.5MR^2)

W=1.9924=.5(.5*1*2.4^2)ω^2

ω=1.15542

WRONG. I can't figure out where I am going wrong, please help!

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