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Missing something

  • Thread starter elemnt55
  • Start date
  • #1
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A CD has a mass of 18.0 g and a radius of 6.11 cm. When inserted into a player, the CD starts from rest and accelerates to an angular velocity of 19.6 rad/s in 0.768 s. Assuming the CD is a uniform solid disk, determine the net torque acting on it.

Formula im using: .5MR^2 for the I which = 25.5208
Then the w= chg in radians/ chg in time
Then the a = chg in w/ chg in time

Net torque = Ia

so i get 1827.33J which isnt right

i also tried converting the g into kg and the cm into m but got wrong answer
 

Answers and Replies

  • #2
Doc Al
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elemnt55 said:
Formula im using: .5MR^2 for the I which = 25.5208
25.52 rad/sec^2 is the angular acceleration, not the rotational inertia.

What did you calculate for I? (Yes, convert to standard units: kg & m)
 

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