A spaceship traveling at 0.50c away from Earth launches a secondary rocket in the forward direction at 0.50c relative to the spaceship. As measured by Earthlings, how fast is the secondary
Rocket moving away from Earth?
A) c
B) 0.70c
C) 0.50c
D) 0.80c
E) 0.90c

Question

Quizplus · Accepted Answer

The velocity of the secondary rocket as observed from Earth is calculated using the relativistic velocity addition formula: $v = \frac{v_1 + v_2}{1 + \frac{v_1 \cdot v_2}{c^2}}$, where $v_1 = 0.50c$ and $v_2 = 0.50c$. Substituting these values, we get $v = \frac{0.50c + 0.50c}{1 + \frac{(0.50c)(0.50c)}{c^2}} = \frac{1.0c}{1 + 0.25} = \frac{1.0c}{1.25} = 0.80c$.

A Spaceship Traveling at 0