A ball balanced on a vertical rod is an example of

CONCEPT

• Equilibrium: It is a state where resultant of all forces acting on a body is zero.

• Stable equilibrium: A system is said to be in stable equilibrium if, when displaced from equilibrium, it experiences a net force or torque in a direction opposite the direction of the displacement.

• The potential energy is minimum in this case.

• Unstable equilibrium: A system is in unstable equilibrium if, when displaced from equilibrium, it experiences a net force or torque in the same direction as the displacement from equilibrium.
  • The potential energy is maximum in this case.

• Neutral equilibrium: A system is in neutral equilibrium if its equilibrium is independent of displacements from its original position.
  • The potential energy remains constant in this case.

EXPLANATION

• If a ball is placed on vertical rod, it is in unstable equilibrium because once it is displaced from its place, it will experience the net force in the direction of displacement and never come back to its original position.
• The potential energy of the ball is maximum at this point.

∴ Option 2 is correct.