Answer:
the answer is
Explanation:For equilibrium
Weight = Tension
mg=T
∴T=4×3.1π=12.4πN (as can be inferred from the question)
Y=
△l/l
T/A
=
1000
0.031
/20
12.4π/π(
1000
2
)
2
=
4×0.031
12.4×20×1000×(1000)
2
=2×10
12
N/m
2
Formula for kinetic energy is 1/2mv^2 so that answer should most probably be 94521.6J
Answer: you want your input force harder
Explanation:
It's D. By "net" they mean the overall force the object experiences, so sum all the force vectors, those in a negative direction (eg friction) should be subtracted.
The speed of sound in normal air is approximately

. In helium, instead, it is

. The mixture of gases mentioned in the problem is made of 97 % of helium and 3% of normal air, therefore the speed of sound in this mixture will be

So, the ratio between the speed of sound in this mixture of gases and in normal air is

The frequencies of the formants of the diver's voices are proportional to the speed of sound, therefore they will change by the same proportion as the speed of sound does. So, the frequencies will be 2.76 times higher than in normal air.