Question 20
DynamicsA stone was dropped from the top of a building 40m high. Find, correct to one decimal place, the time it took the stone to reach the ground. [Take g = 9.8ms−2]
- A.2.9 seconds
- B.2.8 seconds
- C.2.6 seconds
- D.1.4 seconds
Show the answer and explanation
Answer: A (2.9 seconds)
Explanation
40 = ½ × 9.8 × t², so t² = 8.16 and t ≈ 2.86 ≈ 2.9 s.