Homework Help Forum: Physics

Posted by Anonymous on Wednesday, May 6, 2009 at 10:21pm.

Astrotrain, a Decepicon triple changer, is traveling at a speed of .77c towards Earth, as seen by Blaster, who is on Earth inside Fortress Maximus. Astrotrain's computers tell him the icon rocket was fired at .35c. Determine the length of the ion rocket as seen by Blaster and Fortress Maximus.

• Physics - RickP, Wednesday, May 6, 2009 at 10:32pm

  Um, how can one determine a relativistically affected length, if no length at all is given in the problem?

  
  

• Physics - Anonymous, Wednesday, May 6, 2009 at 10:37pm

  I apoligize. I forgot to include that Astrotrain fired a 3m ion rocket at Fotress Maximus.

  
  

• Physics - drwls, Thursday, May 7, 2009 at 2:48am

  The speed of the rocket relative to Earth must first be computed. There is a relavistic velocity-addition formula for that. You can find it at http://en.wikipedia.org/wiki/Velocity-addition_formula The value for the relative velocity is v = (.77c + 0.35c)/[1 + (0.77*0.35)] = 0.882 c Now use the Fitz-Gerald contraction formula for the apparent length of the rocket, L', as seen from Earth L' = L * sqrt[1 - (v/c)^2]= 0.471 L = 1.41 m

  
  

Answer this Question

First Name:
School Subject:
Answer: