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## Homework Statement

Star Trek Question: An enemy Klingon space ship moves away from Earth at a speed of 0.80c. The Starship Enterprise gives chase and pursues at a speed of 0.90c relative to the Earth. Observers on Earth see the Starship Enterprise overtaking the enemy ship at a relative speed of 0.1c. With what speed is the Starship Enterprise overtaking the Klingon spaceship, as observed by the crew of the Enterprise?

## Homework Equations

[tex]V_{a/c} = \frac{V_{a/b} + V_{b/c}}{1 + (V_{a/b} V_{b/c})/c^2}[/tex]

[tex]U'_x = \frac{U_x - V}{1 - (U_x V)/c^2}[/tex]

## The Attempt at a Solution

I used this formula:

[tex]U'_x = \frac{U_x - V}{1 - (U_x V)/c^2}[/tex]

Sub in the value where, [tex]U_x = 0.80c[/tex] [tex] V = 0.90c[/tex]

Then i obtained the answer, [tex]U'_x = -0.357c[/tex]

Is this correct?

Also, can someone explain to me what each symbol of the 2 formula means?(the lecture wasn't very clear)

[tex]V_{a/c} = \frac{V_{a/b} + V_{b/c}}{1 + (V_{a/b} V_{b/c})/c^2}[/tex]

[tex]U'_x = \frac{U_x - V}{1 - (U_x V)/c^2}[/tex]

Any help will be greatly appreciated.