Question

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Answer 1

Answer:

71 percent

About 71 percent of the Earth's surface is water-covered, and the oceans hold about 96.5 percent of all Earth's water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the ground as soil moisture and in aquifers, and even in you and your dog.

Answer 2

22hz

The mechanical strain

=lΔl=αΔT=1.21×10−5×20=2.42×10−5

The tension in wire

=T=YlΔlA=2×1011×2.42×10−5×10−6=48.4N

∴ speed of wave in wire

v=μT

=0.148.4

=22m/s

Since the wire is plucked at 4l from one end

The wire shall oscillate in 1st overtone (for minimum number of loops)

λ=l=1m

Now V=fλ or f=λV=22 Hz.