- #1
terryds
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Homework Statement
Plane A flies with speed 0.6c chasing plane B which speed is 0.4c . Both speed is measured by observer on Earth. Then, plane B fires a small rocket which rest mass is 10 kg towards plane A. Rocket speed is 0.2c relative to plane B where c equals the speed of light in vacuum.
What's the speed of the rocket relative to the Earth?
Homework Equations
##V = \frac{V' + u}{1 + \frac{V' u}{c^2}} ## (reverse Lorentz transformation)
The Attempt at a Solution
So, I think the stationary frame is the Earth. The moving frame is plane B. The event is the rocket.
I put
V' = -0.2 c (because A chases B, then B fires a rocket towards A which means opposite direction of the plane), u = 0.4 c (because the moving frame is plane B, I define positive direction is the direction of the plane)
But, I get V = 0.217 c which means that the rocket has the same direction to those planes according to the observer in the Earth.
I think it should be negative sign.
Please help me where I got wrong.
The solution is -0.56 c but I don't know how to figure it out