To determine how long it took for the compass to strike the bottom after being dropped from a height of 240 meters, we can use the formula for the time of free fall under the influence of gravity:
[
d = \frac{1}{2} g t^2
]
where:
- (d) is the distance fallen (240 meters),
- (g) is the acceleration due to gravity (approximately (9.81 , \text{m/s}^2)),
- (t) is the time in seconds.
Rearranging the formula to solve for (t):
[
t^2 = \frac{2d}{g}
]
Substituting the values:
[
t^2 = \frac{2 \times 240 , \text{m}}{9.81 , \text{m/s}^2}
]
Calculating the right side:
[
t^2 = \frac{480}{9.81} \approx 48.94
]
Now, taking the square root to find (t):
[
t \approx \sqrt{48.94} \approx 7.0 , \text{seconds}
]
Thus, the time it took for the compass to strike the bottom is approximately 7.0 seconds.
The correct answer is 7.0 seconds.