The orbital period of a satellite is 2 x 106s and its total radius is 2.5 x 1012 m. the tangential speed of the satellite, written in standard notation, is m/s.

Don't be blinded by all the super-technical stuff about satellites and orbits here.

All it's asking you is:

  --  here's the radius of a circle
  --  here's how long it takes to go around the circle
  --  how fast are you traveling around the circle ?

I hope that's less scary.


Circumference of a circle =

                           (pi) x (diameter)

                        = (pi) x (2 x radius)

                        =  (5 pi) x 10¹² meters .

Time to go around the circle =  2 x 10⁶ seconds

Speed = (distance) / (time)

           = (5 pi x 10¹² m) / (2 x 10⁶ sec)

           =  2.5 pi x 10⁶  m/s

           =       7.85 x 10⁶  m/s

Iagree c would be the answer