The effect of air resistance, how long a stone takes to drop off a 125m high building, landing on the ground, take g=10m/s2:
Correct answer: D. 5 sec
- A. 3 sec
- B. 4 sec
- C. 18 sec
- D. 5 sec
Explanation
To determine the time it takes for a stone to drop from a height of 125 meters, we can use the formula for free fall:t = √(2h/g)Where:t = time in secondsh = height in meters (125m)g = acceleration due to gravity (10m/s²)Substituting the values into the formula:t = √(2 * 125 / 10) = √(25) = 5 secondsThis means the stone will take 5 seconds to hit the ground. The other options are incorrect because:Option A (3 seconds) is too short for the height of 125m.Option B (4 seconds) also underestimates the time required for such a drop.Option C (18 seconds) miscalculates the fall time by a large margin, significantly exceeding the expected duration.Therefore, the correct answer is Option D: 5 sec.
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