Lighter mass leads to faster terminal velocity with air resistance

Steps:

• Air resistance force depends on cross-sectional area and speed, same for both stones due to identical dimensions.
• Gravitational force is mg; smaller mass means smaller weight, so drag-to-weight ratio is higher for the lighter stone.
• Net acceleration a = g - (drag)/m decreases faster for the lighter stone, causing quicker approach to terminal velocity (where a=0).
• Thus, distance vs. time for lighter stone curves concave-down sooner than the dashed line for the heavier stone.

Why C is correct:

• C depicts a curve bending over earlier, matching the lighter stone's faster terminal velocity per drag-to-weight ratio.

Why the others are wrong:

• A: Straight line ignores air resistance, unlike the dashed curve.
• B: Slower initial fall contradicts equal early acceleration before drag dominates.
• D: Steeper curve implies less air resistance effect, suiting heavier mass.

Final answer: C