well, one revolution is 2π radians, so 240 revolutions/min will just be
[tex]\cfrac{240~~~\begin{matrix} r \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~ }{min}\cdot \cfrac{2\pi }{~~\begin{matrix} r \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~ }\implies \cfrac{480\pi}{min}\implies 480\pi \frac{rad}{min}[/tex]
well, v = rω, and since we know ω from above, so
[tex]\omega=\cfrac{480\pi}{min}\qquad \qquad v=\left( \cfrac{1.8}{2}ft \right) \left( \cfrac{480\pi}{min} \right)\implies v=\cfrac{432\pi~ft}{min} \implies v\approx 1357\frac{ft}{min}[/tex]
