Maximum height from kinematic equation

Steps:

• At maximum height, final velocity v = 0 m/s.
• Initial velocity u = 15 m/s upwards; acceleration a = -g ≈ -10 m/s².
• Use v² = u² + 2as to get 0 = (15)² + 2(-10)s.
• Solve: s = (15)² / (2 × 10) = 225 / 20 = 11.25 m ≈ 11 m.

Why B is correct:

• It matches the formula h = u² / (2g), derived from Newton's laws for constant acceleration.

Why the others are wrong:

• A: Likely from misapplying time of flight or using g incorrectly (e.g., h = ut/2 with wrong t).
• C: From h = u² / g (omitting the 2 in denominator).
• D: From h = u² / 2 (forgetting to divide by g).

Final answer: B