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!