Physics, asked by adilmannan007, 10 months ago

A pebble is dropped freeely ina well from its top. It takes 20s for the pebble to reach the water surface in the well. Taking g=10 m/s² and the sleed of sound=330 m/s, find : (i) the depth of water surface, and (ii) the time when echo is heard after the pebble is dropped.

Answers

Answered by khushal546
1

Explanation:

since when pebble is in hand it's initial velocity is zero

here u=0

g=10m/s²

t=20sec

x=?

from equation of motion

s=ut+1/2gt²

s=0*20+1/2(10*20)

s=0+100

s=100m

time of hearing of echo

s=ut+1/2at²

100=0*t+1/2(10*t²)

10t²=200

=20

t=4.47sev

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