a spaceship travels at 0.3c in respect to Earth. at t=0 she launches a missile that travels at 0.6c in respect to her and in the same direction of her. at t=7 secs the ship fires a laser that hits the missile and make it explode. how many secs will take the light from the explosion to reach the spaceship in respect to her from the moment t=0??

Question

anonymous · Answer

it might help to know that I all ready found the speed of the missile in respect of earth which is 0.763c

and I already found the time it takes the laser to reach the missile in respect for the missile which is 14 secs

souvik · Answer

is it related to relativity?

anonymous · Answer

it  Relativistic Velocity Transformation

anonymous · Answer

I have not done anything like this but I would think all you need to do is use her reference frame (in which the missile was traveling at .6c) to find the distance traveled by the missile before the laser goes off. Include the distance traveled by this missile while the laser is moving towards it for the final distance traveled. Then just find how long it will take the light from the explosion will take  to reach her. 

So it looks like it would be 14*3e8 - 14*.3*3e8 for the distance from her to the explosion initial. And now just find the time it takes like to traverse that distance as she moves towards it.

theeric · Answer

This is "special relativity." I honestly need a refresher. I'll look on the internet!

theeric · Answer

I'm sorry, I think this is a little over my head at the moment. Good luck!

theeric · Answer

The measurement of spaceship speed with respect to Earth... Is it necessary? Isn't every other measurement with respect to the ship?

Also, this is all I have, but my mind ceases to recall the relevant material...
|dw:1372997356101:dw|But I don't trust myself to determine much else!
Again, good luck! I thought I'd offer what insight I have. Not something to go off of, but something to think about.