Use the formula $s=r \omega t$ to find the value of the missing variable. $\omega=\frac{\pi}{2}$ radians per sec, $r=8 \mathrm{~cm}, t=6 \mathrm{sec}$ \[ \mathrm{s}=\square \mathrm{cm} \] (Type an answer, using $\pi$.)

Step 1 ：Given that the formula for the arc length of a circle is \(s = r \omega t\), where \(r\) is the radius, \(\omega\) is the angular velocity, and \(t\) is the time.

Step 2 ：Substitute the given values into the formula: \(r = 8 cm\), \(\omega = \frac{\pi}{2} radians/sec\), and \(t = 6 sec\).

Step 3 ：Calculate the arc length: \(s = 8 cm * \frac{\pi}{2} radians/sec * 6 sec\).

Step 4 ：Simplify to find that \(s \approx 75.40 cm\).

Step 5 ：Final Answer: \(\boxed{75.40 cm}\)