## Physics Technology Update (4th Edition)

$v=1.2\times 10^{-5}m/s$
To find the angular speed, use dimensional analysis. $$\frac{2\pi rad}{12hr} \times \frac{1hr}{60min} \times \frac{1min}{60s}=1.45\times 10^{-4} rad/s$$ Since the tangential speed is equal to $$v=r\omega$$ substituting known values of $\omega=1.45\times 10^{-4}rad/s$ and $r=8.2cm=0.082m$ yields a tangential speed of $$v=(0.082m)(1.45\times 10^{-4}rad/s)=1.2\times 10^{-5}m/s$$