# This equation?

1. Mar 7, 2005

2. Mar 7, 2005

### HallsofIvy

Staff Emeritus
Where is this from? That looks like a not-very-good translation into English from another language. The final question should be "How fast did he have to be going in order for his claim to be true?", NOT "How quickly he had to move in order his claim to be true."! Of course my (whatever was the original language) is non-existant so I can't complain.

There is clearly a problem with the PDF conversion (unfortunately, Adobe is not perfect and if this was originally done in some other language, there may have been non-standard characters used that Adobe did not recognize.)

I'm not certain what was supposed to be there but I do note that 630/560 = 1.125, 1 and 1/8 so that 1/8= 630/560- 1.

Perhaps the formula was intended to be
$$\frac{l}{l'}= 1-\frac{v}{c}$$

Then
$$\frac{v}{c}= 1- \frac{l}{l'}$$
which, with the values given would be 1/8.