Chapter 3: Derivatives - Practice Exercises - Page 181: 114

$5~rad/sec$.

Step 1. We are given $v=6ft/sec, r=1.2ft$ Step 2. Using the equation $s=r\theta$, take $r$ as a constant. Here, we have $v=\frac{ds}{dt}=r\frac{d\theta}{dt}$ and $\frac{d\theta}{dt}=\frac{v}{r}=\frac{6}{1.2}=5rad/sec$.