A stone is dropped from rest from the top of a cliff. After 3.0 seconds of free fall, what is its speed? Use g = 9.8 m/s² and ignore air resistance.
A9.8 m/s
B19.6 m/s
C29.4 m/s
D88.2 m/s
Explanation
📌 In free fall from rest, v = v₀ + gt = 0 + 9.8 × 3.0 = 29.4 m/s. Distractor A gave speed at 1 second; B at 2 seconds; D confused this with v = ½gt² which gives distance fallen (which would still be wrong because ½ × 9.8 × 9 = 44.1, not 88.2 — D represents a compounded arithmetic slip).