A man who weighs 60 kg on earth, weighs 61 kg on a rocket as measured by an observer on the earth. What is the speed of the rocket?

4.5 × 10^7 m/s

5.5 × 10^7 m/s

8.5 × 10^10 m/s

None of these

Using the relativistic mass equation:

m = m0 / sqrt(1 - v^2/c^2)

Rearranging to solve for v:

v ≈ sqrt(1 - (m0/m)^2) × c

Plugging in the values:

v ≈ sqrt(1 - (60/61)^2) × 3.0 × 10^8 m/s

≈ 4.5 × 10^7 m/s