Easy angular velocity question

[renob]

Homework Statement

A solid disk with a radius of 1.4cm is a rest. The disk has 2.0m of string wound on to its circumference. The string is pulled off the disk by a constant force in a time of 7.3s. What is the final angular velocity of this disk?

Homework Equations

v = r*ω

The Attempt at a Solution

The correct answer is 39.1 rad/s but I keep getting half of that (19.6 rad/sec).

Since ω = v/r, I solve for v:

2m/7.3 sec = 0.274 m/s

then ω = (0.274 m/s)/(0.014 m) = 19.6.

what am I doing wrong? the correct answer is 39.1

 

[DukeLuke]

Does a constant force mean you have constant velocity or acceleration?