Angular acceleration and displacement problem

[Lotus93]

I've listed the whole problem because I know I'll have more questions, but all I want to know atm is whether I'm plugging the right values into the equation. Thanks in advance for your help.

Homework Statement

A compact disc speeds up uniformly from rest to 5200rpm in 620rad. The disc’s diameter is 5.0cm.

a. What is the angular acceleration in rad/s^2?
b. How long does it take to reach this speed?
c. What is the total angular displacement in degrees?
d. How many revolutions does the disc make in this time?
e. What is its centripetal acceleration at maximum speed?

Homework Equations

θ = (1/2)αt²
ω_f² = ω_i² + 2αθ

The Attempt at a Solution

For part A, first I would convert angular velocity to rad/sec
So 5200 rot/min = (5200*2pi) rad/(60 sec) = 544 rad/sec
Since I don't know time yet, I would use the second equation above.

The first thing I want to ask is if my values for ω_f, ω_i, and θ are correct.
ω_f, = 544
ω_i = 0
θ = 620 radians

 

[haruspex]

Yes. As a matter of technique, I always keep things in algebraic variable form (i.e. using the labels for the quantities) until I have the final equation, and only then plug in the constants. This makes it easier to find algebraic errors, easier for others to follow, and avoids propagation of rounding errors.