Question

Rajiv puts a piece of wood on a pivot. He adds weight at different distances from the pivot until the wood balances. Weight B is heavier than weight A. Explain why Rajiv moved weight A nearer to the pivot.

a) Rajiv moved weight A nearer to the pivot to increase the overall weight on that side.
b) Rajiv moved weight A nearer to the pivot to decrease the overall weight on that side.
c) Rajiv moved weight A nearer to the pivot to maintain balance.
d) Rajiv moved weight A away from the pivot, not nearer.

Answer 1

Rajiv moved weight A closer to the pivot to maintain balance by balancing the torques since Weight A is lighter and needs to be closer to achieve equilibrium on the seesaw.

Step-by-step explanation:

Rajiv moved weight A nearer to the pivot to maintain balance on the piece of wood. By doing this, he adjusted the torque created by the weights, which is the product of the weight and its distance from the pivot point. Since weight B is heavier than weight A, placing weight A closer to the pivot decreases its lever arm length, which is the distance from the pivot, thus reducing its torque. This action compensates for the larger torque produced by the heavier weight B being further from the pivot, allowing both sides to have equal torque and hence be in balance. This is in accordance with the principle of leverage explained by the second condition for equilibrium, which states that for an object to be in equilibrium, the sum of all torques acting on it must be zero.