A 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\(^{-2}\)]
-
2.9.seconds
- 2.8 seconds
- 2.6 seconds
- 1.4 seconds
The correct answer is: A
Explanation
s = \(\frac{1}{2}gt^2\)
40 = \(\frac{1}{2} \times 9.8 \times t^2\)
\(\frac{80}{9.8} = t^2\)
t = \(\sqrt{8.16326}\)
t ≈ 2.9 secs