How many seconds will it take a flywheel to reach 1300rpm? It has a mass of 375kg and diameter of 1.7m?

Question

Flywheels are large, massive wheels used to store energy. They can be spun up slowly, then the wheel's energy can be released quickly to accomplish a task that demands high power. An industrial flywheel has a 1.7 m diameter and a mass of 375 kg. A motor spins up the flywheel with a constant torque of 60 N m. How long does it take the flywheel to reach top angular speed of 1300 rpm?

Answer 1

I'm not 100% certain I did this right, so please bear that in mind:

1.7m diameter, which means 0.85m radius.

I assume the torque is applied along the circumfrence of the wheel?  If so, then

60 N-m / .85 m = 70.6 N of force

70.6 N / 375 kg = 0.188 m / s^2 (acceleration)

1300 rpm * (1.7 * pi) / 60 = 115.8 m/s <-- velocity that we want to reach

115.8 m/s / 0.188 m/s^2 = 615.5 seconds

Like I said I'm not entirely sure about that!  It's been a few years since I've taken a mechanics class!