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**[SOLVED] Relativistic Doppler Effect and a Baseball**

## Homework Statement

A baseball coach uses a radar device to measure the speed of an approaching pitched baseball. This device sends out electromagnetic waves with frequency [tex] f_0 [/tex] and then measures the shift in frequency [tex] \Delta f [/tex] of the waves reflected from the moving baseball.

If the fractional frequency shift produced by a baseball is [tex]\frac{\Delta f}{f_0}[/tex] 2.88×10−7, what is the baseball's speed? (Hint: Are the waves Doppler-shifted a second time when reflected off the ball?)

## Homework Equations

[tex] u = \frac{c((\frac{\delta f}{f_0})^2) - 1}{\frac{\delta f}{f_0})^2 + 1} [/tex]

## The Attempt at a Solution

I tried putting the variables in, but becasue there is a double doppler shift, the asnwer was incorrect. Was is the best way to do this question when a Double Shift occurs?

Any ideas gratly appreciated,

TFM

Edit: in the formulas, that should be a big Delta not a small Delta, Sorry