Problem: A rotating platform of radius R = 4.2cm is initially at rest. It then begins to move, such that a point on its edgeexperiwnces a tangential acceleration of at = 7.5cm/s^2.

A) Write an [expression] that gives the radial acceleration on the edge of the platform as a function of time.

B) Write an [expression] for the time at which the magnitudes is the radial and tangential accelerations at the edge will be equal.

C) Calculate the time, t in seconds, when the magnitudes of the radial and tangential accelerations are equal.