Question

to estimate the height of a bridge over a river a stone is dropped freely in the river from the bridge the stone take 2 sec to touch the water surface in the river calculate the height of the bridge from the water level
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Answer 1

Answer:

By second equation of moth

$s=ut+\frac{1}{2}at^{2} =0(2)+\frac{1}{2}(9.8)2^{2}=19.6m$

Answer 2

Answer:

Answer Expert Verified

The stone is being dropped freely from rest hence, the initial velocity of the stone, u = 0. Again, the velocity of the stone increases as it comes down. Hence, the acceleration due to gravity 'g' is to be taken as positive.