You have a long board balanced on a rock. When you place a heavy object on one side, the board tilts down. Consider the following changes, Which of these changes would most effectively bring the board back to balance?

Answer: C. Move the heavy object to the centre of the board.

Balance depends on the torque, which is the weight of the object multiplied by its distance from the pivot (the rock). Moving the object to the center reduces this distance to zero, eliminating its turning force and allowing the board to level out.

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