Answer:
Explanation:
Velocity of sound in air at 20 degree = 343 m/s
Velocity of sound in water at 20 degree = 1470 m/s
Time taken in to and fro movement in air
=( 2 x 10) / 343 = 0.0583 s
Rest of the time is
.171 - .0583 = .1127 s
This time is taken to cover distance in water. If d be the depth of lake
2d / velocity = time taken
2 d / 1470 = .1127
d = 82.83 m
This is 2 hertz. You can mark out 2 full wavelengths in the second of time.
<span>The mass of an electron is not significant to the overall mass of the atom. (B)
It takes roughly 1,850 electrons to equal the mass of ONE proton or neutron,
but the most complex atom has only around 100 of them.</span>
<span> energy produced by flow of electric charge describes a electrical energy
because movement of electric charge do effect the work on system
so correct option is B
hope it helps</span>
