Gravity Serious satellite

Circumference = $2 \times \pi \times r$

$r = 42250$ then, the circumference is = $84500 \pi$

$V (Km/h) = \frac {84500 \pi}{24} = \approx11061.0241...$

To convert it to Km/s we need to multiplicate $\approx 11061.0241...$ by $0.000277777778$ , which will results in $\boxed { \approx3.072...}$

$v = \omega r$ $\omega = 1\frac{\text{rev}}{\text{day}} \times 2\pi\frac{\text{rad}}{\text{rev}}\times \frac{1\ \text{day}}{86400\ \text{s}} \approx 7.27\times 10^{-5} \frac{\text{rad}}{\text{s}}$ $r = 42250\ \text{km}$ $v = (7.27\times 10^{-5} \frac{\text{rad}}{\text{s}})\times 42250\ \text{km}\approx \boxed{3.07\ \text{km/s}}$