Question

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 × 104 m/s
7.7 × 104 m/s
5.1 × 105 m/s

Answer 1

v = 2πr / T = 2π(1.8×10^8 m) / (2.2×10^4 s)
≈ (2π × 0.8182) × 10^4 m/s ≈ 5.14×10^4 m/s

So 5.1 × 10^4 m/s.