What is the approximate tangential speed of an object orbiting Earth with a radius of 1.8 × 108 m and a period of 2.2 × 104 s?

7.7 × 10^–4 m/s
5.1 × 10^4 m/s
7.7 × 10^4 m/s
5.1 × 10^5 m/s