Chapter 10 - Rotational Kinematics and Energy - Problems and Conceptual Exercises - Page 328: 81

$6.8rad/s$

We know that $\Delta \theta=2\frac{1}{2}rev$ $\implies \Delta \theta=2.5rev$ Now $\omega=\frac{\Delta \theta}{t}$ We plug in the known values to obtain: $\omega=\frac{2.5rev}{2.3s}$ $\implies \omega=1.0869rev/s$ $\implies \omega=(1.0869rev/s)(\frac{2\pi \space rad}{1rev})$ $\omega=6.8rad/s$