# Expression of the force derived from this potential

Andrei0408
Homework Statement:
Knowing that the potential is U = - α / r , where α is a positive constant and r the distance from the
potential field source, find the expression of the force deriving from this potential; Give examples of forces that derive from such a potential.
Relevant Equations:
Not sure
I just don't know what equations I should use, or what exactly I need to do. I just need some guidelines, thank you!

It is a well known fact that given the potential function ##U(r,\theta,\phi)## of a field , the force that the field applies to a test point charge (or test point mass or whatever is the field subject)## q## is given by $$\vec{F}=-q\nabla U$$.
So all you have to do is calculate the gradient ##\nabla U## of the function ##U##. I assume from the context that the calculation must be done in spherical coordinates. So it will be $$\nabla U=\frac{\partial U}{\partial r}\hat r+\frac{1}{r}\frac{\partial U}{\partial \theta}\hat\theta+\frac{1}{r\sin\theta}\frac{\partial U}{\partial \phi}\hat\phi$$
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