Answer:
Light does not need a medium to travel travel through, but since waves must have a medium to vibrate, sound is not created where no air is present.
Explanation:
The correct answer is - a. was a sign of danger.
Once the people saw that the ocean waters are receding and were living vast space without water behind them, they knew that something big and very dangerous will happen. And in fact it did. The water that was sucked in in the place were there was a crack on the ocean floor, got shot back under big pressure and it had very big speed, as well as having waves that were destroying anything on their way.
Answer:
a) The velocity is 2.94m/s
b) 0.441
Explanation:
a) Assume gravity is 9.8m/s^2
Use the equation below to solve for the velocity at 0.30 seconds
,
vf =unknown velocity vi= initial velocity vi=0m/s a= 9.8m/s^2 t=0.30seconds
Step 1: Substitute the variables with the knowns

Step 2: Solve

b)
Use the equation below to solve for the displacement at 0.30 seconds

Step 1: Substitute the same variables with the knowns

Note that vi*t=0 as vi=0m/s
Step 2: Solve
x=0.441m
To solve this problem we will apply the concepts related to wavelength, as well as Rayleigh's Criterion or Optical resolution, the optical limit due to diffraction can be calculated empirically from the following relationship,

Here,
= Wavelength
d= Diameter of aperture
= Angular resolution or diffraction angle
Our values are given as,

The frequency of the sound is 
The speed of the sound is 
The wavelength of the sound is

Here,
v = Velocity of the wave
f = Frequency
Replacing,


The diffraction condition is then,

Replacing,

d = 0.24 m
Therefore the diameter should be 0.24m