Center of mass at balance point

Steps:

• Identify the pivot: the table edge where the hook and pencil balance.
• Recall that for static equilibrium, the center of mass must align vertically over the pivot to prevent tipping.
• Analyze the system: the hook's mass pulls one side, pencil's mass the other, but net torque is zero only if CM is at the pivot.
• Conclude the CM position is directly at the balance point on the edge.

Why B is correct:

• B marks the pivot edge, where the CM must be for torque balance per Newton's first law (net torque = 0).

Why the others are wrong:

• A is left of pivot: would cause clockwise torque and tipping left.
• C is right of pivot: would cause counterclockwise torque and tipping right.
• D is above/below pivot: misaligns horizontally, violating equilibrium condition.

Final answer: B