Geometric Interpretation of √(x^2+y^2+z^2) and its Derivative

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SUMMARY

The discussion centers on the geometric interpretation of the expression √(x^2+y^2+z^2) and its derivative, specifically the gradient. It is established that the gradient of the scalar function r, defined as r = √(x^2+y^2+z^2), is given by ∇r = \vec{r}/r. This indicates that the gradient points in the direction of the position vector, reinforcing that the rate of change of r in the direction of r is equal to 1. The unit vector \vec{u_{r}} represents the direction of maximum change of the distance from the origin.

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Let r = √(x^2+y^2+z^2)
One can easily show that \nablar= \vec{r}/r.
But I'm having a hard time understanding what this means geometrically - who can help? :)
 
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Not that this is a proof, but intuitively the direction of the gradient of a scalar function gives the direction of maximum change of the value of that function. Since your scalar function is the distance from the origin, and it makes sense that the direction of the gradient is in the direction of \vec{r}= r\vec{u_{r}}.<br /> <br /> Grad(r) = \frac{\vec{r}}{r} = \frac{r\vec{u_{r}}}{r} = \vec{u_{r}}, the unit vector in the direction of the position vector. That makes sense, because the rate of change of r as you move in the direction of r is 1.
 

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