Homework Help: Rotational Motion

Heres the problem Im workin on

http://img294.imageshack.us/img294/9166/rotatesm3.jpg [Broken]

Now in order to find the magnitude of accleration Im assuming I would need to find the two components of acceleration first, Centripetal and Tangential......

I found tangetial by the formula

[tex] a_{t} = r\alpha [/tex]


I converted the 2 revolutions to

[tex] 4\pi radians [/tex]

but im not exactly sure how to get tangential...i need angualr velocity......

how to I get angular velocity from revolutions?

 

ok how does this look

[tex] \omega^2 = \omega_{o} + 2\alpha(\theta-\theta_{o})[/tex]

[tex]= 0 + 2(.8)(4\pi radians)[/tex]

[tex]\omega = 4.48 rad/s[/tex]



[tex]a_{n} = r\omega^2 = (.6)(20.16) = 27.18 [/tex]

[tex] a_{t} = r\theta = (.6)(.8) = .480 [/tex]

[tex]A = \sqrt{(9.480)^2 + (27.18)^2} = 27.18 [/tex]

 

ohhh thanks....im having trouble reading my calculators display!

that changes the answer to 12.09 rad/s^2