Position-time graph for free fall in uniform gravity

Steps:

• In a uniform gravitational field, objects experience constant acceleration g downward.
• The position y as a function of time x follows y = y0 - (1/2)gt^2 (for initial velocity zero).
• This quadratic equation produces a parabolic curve opening downward.
• Match the diagram's shape to this parabolic variation.

Why B is correct:

• Option B depicts a downward-opening parabola, consistent with the kinematic equation for constant acceleration.

Why the others are wrong:

• A shows a straight line, implying constant velocity, not acceleration.
• C shows an upward parabola, suggesting upward acceleration, opposite to gravity.
• D shows a horizontal line, indicating no motion or constant position.

Final answer: B