- #1
Ryomega
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Homework Statement
Show that Ui [itex]\frac{dU^i}{d\tau}[/itex] = 0
Homework Equations
Raising Indices: Ui = gkiUi = Ui
where gk is a dummy index
The Attempt at a Solution
I'm interpreting this question to mean a scalar multiplying each component of a four vector = 0. Also, since the same index is used twice, once raised and once subscript, this implies summation.
So the sum of vector components multiplied by a scalar is 0? Since when?
I'd imagine I'm misunderstanding something, your help is much appreciated!
Thank you!