# Angular velocity

A torque of 10 N m is applied to a 10 kg disk of radius 0.2 m initially at rest. What is the angular acceleration of the disk?

I used I=1/2mr^2 so
1/2*10*0.2^2=.2

(With regard to the previous problem) The applied torque of 10 N m gets the disk rotating starting from rest. What is the angular velocity of the disk about an axis through its center, after it has completed two revolutions?

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tiny-tim
Homework Helper
hi tica86! (have a theta: θ an omega: ω and an alpha: α and try using the X2 icon just above the Reply box )
A https://www.physicsforums.com/library.php?do=view_item&itemid=175" of 10 N m is applied to a 10 kg disk of radius 0.2 m initially at rest. What is the angular acceleration of the disk?

I used I=1/2mr^2 so
1/2*10*0.2^2=.2

looks good! (With regard to the previous problem) The applied torque of 10 N m gets the disk rotating starting from rest. What is the angular velocity of the disk about an axis through its center, after it has completed two revolutions?
you have ωi α and t, and you want θ …

(that's like having vi a and t, and wanting s)

so use the angular version of one of the standard https://www.physicsforums.com/library.php?do=view_item&itemid=204" equations Last edited by a moderator:
hi tica86! (have a theta: θ an omega: ω and an alpha: α and try using the X2 icon just above the Reply box )

looks good! you have ωi α and t, and you want θ …

(that's like having vi a and t, and wanting s)

so use the angular version of one of the standard https://www.physicsforums.com/library.php?do=view_item&itemid=204" equations Ok, so I tried 4*3.14=12.56
square root=12.60??
Is that correct?

Last edited by a moderator:
tiny-tim
hi tica86! (have a square-root: √ and a pi: π and please use the X2 tag just above the Reply box )
uhh? what formula are you using? 