Rotation of Disc: Calculating Angular Velocity

[thereddevils]

Homework Statement

A uniform circular disc at rest has mass 10 kg and radius 0.2m. When a force of 10 N is applied tangentially to the disc for 10s, calculate the angular velocity. Given the moment of inertia, I=1/2 mr^2

Homework Equations

The Attempt at a Solution

Using rF=I(alpha) , alpha = 10 rad/s^2 after substituting r=0.2 , m=10 , F=10

Then, using the rotational formulas,

w = w0 + at (w is meant to be omega)

w = 0+ (10)(10) = 100 rad /s

but the answer given is 10 rad/s .

 

[chaoseverlasting]

Your answer is correct. Unless you've copied the given information incorrectly, the answer given is wrong.

 

[thereddevils]

Your answer is correct. Unless you've copied the given information incorrectly, the answer given is wrong.

This is the working of the answer.

Iw=rt

where I, the moment of inertia, w=angular velocity, r= the radius, and t the time.

and from here, the angular velocity is evaluated. I haven't seen that formula before.

 

[Mindscrape]

Yeah, your answer is right given that the info is correct

$$\omega=\frac{2F}{mr}t$$