Question

The force acting on a body moving along $x$-axis varies with the position of the particle as shown in the figure. The body is in stable equilibrium at

• A. $x=x_{1}$
• B. $x=x_{2}$
• C. both $x_{1}$ and $x_{2}$
• D. neither $x_{1}$ nor $x_{2}$

Answer 1

Answer: (B)

When particle moves away from the origin, then at position $x=x_{1}$, force is zero and at $x>x_{1}$, force is positive (repulsive in nature). So particle moves further and does not return back to original position, i.e., the equilibrium is not stable.
Similarly, at position $x=x_{2}$, force is zero and at $x>x_{2}$, force is negative (attractive in nature).
So, particle returns back to original position, i.e., the equilibrium is stable.