Answer
$66637.17\text{mph}$
Work Step by Step
The distance from the Sun to the Earth is: $r=9.29\cdot10^7$ miles.
The Sun takes $365$ days($=365\cdot24$ hours) to make a revolution, hence its angular velocity is: $\omega=\frac{2\pi}{t}=\frac{2\pi}{365\cdot24}=7.173\cdot10^{-4}\frac{\text{rad}}{\text{hr}}.$
Therefore the linear velocity:
$v=\omega r\\v=7.173\cdot10^{-4}(9.29\cdot10^7)=66637.17\text{mph}$
