A disk has a constant angular acceleration of 4.00 rad/s^2 about an axis perpendicular to the disk at its center. Find the radius of a point on the disk, where 0.500s after the disk begins to rotate, the magnitude of the total acceleration (centripetal plus tangential) equals that of the acceleration due to gravity.

I still don't understand.

Question

A disk has a constant angular acceleration  of 4.00 rad/s^2 about an axis perpendicular to the disk at its center. Find the radius of  a point on the disk, where 0.500s after the disk begins to rotate, the magnitude of the total acceleration (centripetal plus tangential) equals that of the acceleration due to gravity.

I still don't understand.

experimentx · Answer

$ a_t = r \alpha \sin\theta $ , if $ \theta =\pi/2$ , $ a = r \alpha $ <-- tangential acceleration at certain point at distance 'r'

$ a_c = v^2/r$, and  $ v = \alpha t$ if $ v = 0 $ at $ t = 0 $

experimentx · Answer

magnitude of resultant acceleration at certain point = $ \sqrt{a_c^2 + a_t^2} $

and for the last part ... I am not really sure at all!!!

anonymous · Answer

thank you.