An easy vector identity I can't prove

Thread starter nathangrand
Start date Mar 23, 2012
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Identity Vector Vector identity

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The discussion revolves around proving the vector identity ∇(U·r) = U in polar coordinates. Participants highlight that the initial assumption of "find U such that..." may not be correct. A suggestion is made to start with the basis vectors for clarity. The conversation emphasizes the need for a mechanical check to validate the identity. Overall, the focus is on understanding the correct approach to proving the vector identity in the specified coordinate system.

Mar 23, 2012

nathangrand

Show the following, where U is a vector, and r is the position vector: \nabla(U.r) = U in polar coordinates

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Mar 23, 2012

sunjin09

A quick mechanical check shows it is not right

Mar 23, 2012

xaos

assuming, "find U such that...", i would start with the basis vectors.

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