Conservation of mechanical energy governs KE vs. h

Steps:

• Ball starts at rest, so initial KE = 0 and initial PE = mgh₀ (h₀ is release height).
• Total mechanical energy E = mgh₀ remains constant (no air resistance).
• At height h above ground, PE = mgh, so KE = E - PE = mg(h₀ - h).
• Thus, KE decreases linearly with increasing h, from KE = mgh₀ at h=0 to KE=0 at h=h₀.

Why D is correct:

• D shows a straight line with negative slope, matching KE = mg(h₀ - h) from energy conservation.

Why the others are wrong:

• A: Curved upward, implies accelerating energy gain not linear.
• B: Curved downward, suggests decelerating fall impossible without resistance.
• C: Horizontal line, violates energy conversion as h changes.

Final answer: D