A boy standing at the top of a tower of 30m height drops a stone. Assuming g=10ms−2 the magnitude of velocity with which it hits the ground is
A
20m/s
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B
24.49m/s
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C
40m/s
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D
10.26m/s
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Solution
The correct option is B24.49m/s Given, g=10ms−2 and h=30m Taking downward as positive, Using third equation of motion, we have v2−u2=2gh ⇒v=√2gh(∵u=0) =√2×10×30 =√600=24.49ms−1