Explain how the sign of the slope of an electric potential energy–versus–separation…

PHYSICS · Subjective · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential

Problem

Explain how the sign of the slope

\frac{dU}{dr}

of an electric potential energy–versus–separation graph reveals whether the electrostatic force between two point charges is attractive or repulsive.