00:01
Okay, we have two starships approaching one another rather quickly.
00:08
All right, and their relative speed is 782 .5 kilometers per second.
00:20
And one of them is sending a signal at a particular wavelength, and we want to know, or one of them receives a signal at a particular wavelength.
00:28
We want to know what wavelength the signal was sent at.
00:31
All right.
00:33
So first we're going to put this in terms of our familiar doppler equation.
00:37
The frequency seen is equal to the frequency emitted times one plus or minus the relative speed over speed of light.
00:49
Now in this case, because they're coming towards each other, oops, because we're coming towards each other, the doppler shift is going to be.
01:05
Positive.
01:07
All right, and we also know that wavelength is equal to c the speed of light over frequency.
01:15
So we're going to replace everything that's in frequency in terms of wavelength to make our problem more straightforward...