Vertical free fall determines time to ground

Steps:

• Initial vertical velocity is 0 m/s; use s = (1/2) g t² for vertical motion.
• Substitute s = 8.0 m, g = 9.8 m/s²: 8 = (1/2)(9.8)t².
• Solve: t² = 16 / 9.8 ≈ 1.63; t = √1.63 ≈ 1.3 s.
• Horizontal velocity does not affect vertical time.

Why C is correct:

• Matches time from s = (1/2) g t², the kinematic equation for free fall with zero initial vertical velocity.

Why the others are wrong:

• A: Underestimates by using g ≈ 20 m/s² or t = √(s/g).
• B: Underestimates by approximating g = 10 m/s² without full calculation.
• D: Overestimates by including horizontal velocity in vertical equation.

Final answer: C