$12\mathrm{.}3$ A Global Positioning System $($GPS$)$ satellite is in a circular orbit $12,580$ mi above the surface of the earth and completes one orbit every $12$ h$.$ Knowing that the magnitude of the linear momentum of the satellite is

$750$

$$

$10$

$3$

lb

$$

s

and the radius of the earth is $3960$ mi$,$ determine $($a$)$ the mass of the satellite, $($b$)$ the weight of the satellite before it was launched from earth.