- #1

affans

- 11

- 0

## Homework Statement

A light signal is sent from the origin of a system K at t = 0 to the point x = 1 m, y = 8 m, z = 13 m. a) At what time t is the signal received?

b) Find ( x', y', z', t' ) for the receipt of the signal in a frame K' that is moving along the x-axis of K at a speed of 0.6c.

## Homework Equations

The lorentz transformations:

x' = [tex]\gamma * (x - vt)[/tex]

y' = y

z' = z

## The Attempt at a Solution

Part a was easy. I got the right answer. I just took the length of the vector given by the co-ordinates and divided by the speed of light. The answer is [tex] 5 * 10^8 [/tex] I am having trouble with part b.

Ofcourse, y' and z' were easy to get. t' (i had 3 tries, and i used them all) so I lost a mark there. I have one try left on x'.

Using the equation, we first have to solve for [tex]\gamma[/tex]. Plugging the numbers into the equation for gamma:

[tex] \frac{1}{\sqrt{1-(v/c)^2}}\; \text{yields} \; 1.25[/tex]

Then using the lorentz transformation I have the following eqn:

x' = [tex]\gamma[/tex] (x - vt) . Plugging in the numbers yeilds

x' = 1.25(1 - 0.6 * c *(5E-8))

I get 10 as the answer. It is wrong. I also thought t = 0 could work since that's when the event happened. But the answer 1.25 is also wrong.

My third attempt yielded 11.25m however, I am scared to submit it. If anyone can please verify my number for me.