Question

The given plot shows the variation of $u$, the potential energy of interaction between two particles with the distance separating them $r$.
1. $B$ and $D$ are equilibrium points
2. $C$ is a point of stable equilibrium
3. The force is interaction between the two particles is attractive between $C$ and $D$ and repulsive between $D$ and $E$
4. The force of interaction between particles is repulsive between points $E$ and $F$. Which of the above statements are correct?

• A. $1$ and $2$
• B. $1$ and $4$
• C. $2$ and $4$
• D. $2$ and $3$

Answer 1

The correct option is C $2$ and $4$

At C, potential energy is minimum. So it is stable equilibrium position.
Further,
$F=-\frac{dU}{dr}=-\text{(Slope of U-r graph)}$
Negative force means attraction and positive force means repulsion.