physics
posted by Meghan .
A disk, with a radius of 0.25 m, is to be rotated like a merrygoround through 800 rad, starting from rest, gaining angular speed at the constant rate α1 through the first 400 rad and then losing angular speed at the constant rate α1 until it is again at rest. The magnitude of the centripetal acceleration of any portion of the disk is not to exceed 400 m/s2. (a) What is the least time required for the rotation? (b) What is the corresponding value of α1?

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