4. If gear A rotates with a constant angular acceleration of

a = 90 rad/s², starting from rest, determine the time required for

gear D to attain an angular velocity of 600 rpm. Also, find the

number of revolutions of gear D to attain this angular velocity.

Gears A, B, C, and D have radii of 15 mm, 50 mm, 25 mm, and

75 mm, respectively.