First we need to find the speed of the dolphin sound wave in the water. We can use the following relationship between frequency and wavelength of a wave:
![v=\lambda f](https://tex.z-dn.net/?f=v%3D%5Clambda%20f)
where
v is the wave speed
![\lambda](https://tex.z-dn.net/?f=%5Clambda)
its wavelength
f its frequency
Using
![\lambda = 2 cm = 0.02 m](https://tex.z-dn.net/?f=%5Clambda%20%3D%202%20cm%20%3D%200.02%20m)
and
![f=22 kHz = 22000 Hz](https://tex.z-dn.net/?f=f%3D22%20kHz%20%3D%2022000%20Hz)
, we get
![v=(0.02 m)(22000 Hz)=440 m/s](https://tex.z-dn.net/?f=v%3D%280.02%20m%29%2822000%20Hz%29%3D440%20m%2Fs)
We know that the dolphin sound wave takes t=0.42 s to travel to the tuna and back to the dolphin. If we call L the distance between the tuna and the dolphin, the sound wave covers a distance of S=2 L in a time t=0.42 s, so we can write the basic relationship between space, time and velocity for a uniform motion as:
![v= \frac{S}{t}= \frac{2L}{t}](https://tex.z-dn.net/?f=v%3D%20%5Cfrac%7BS%7D%7Bt%7D%3D%20%5Cfrac%7B2L%7D%7Bt%7D%20%20)
and since we know both v and t, we can find the distance L between the dolphin and the tuna:
Are you good is every thing alr
The correct answer is: <span>The water and ions lost through perspiration must be replaced during recovery so the body can replenish fluid and stored energy
This is the relation of perspiration to recovery after exercise. That is why it is important to replenish the body with water to avoid dehydration. </span>
Answer:
![\sigma_{max}=3*10^{-5}\frac{C}{m^2}](https://tex.z-dn.net/?f=%5Csigma_%7Bmax%7D%3D3%2A10%5E%7B-5%7D%5Cfrac%7BC%7D%7Bm%5E2%7D)
Explanation:
The electric field on the surface of a conductor is given by:
![E=\frac{\sigma}{\epsilon_0}](https://tex.z-dn.net/?f=E%3D%5Cfrac%7B%5Csigma%7D%7B%5Cepsilon_0%7D)
Here
is the surface charge density and
the permittivity of free space. Thus, the highest surface charge density that can exist in a conductor is given by the value of the dielectric breakdown of the air multiplied by the permittivity of free space:
![\sigma_{max}=\epsilon_oE_{breakdown}\\\sigma_{max}=(8.85*10^{-12}\frac{C^2}{N\cdot m^2})(3*10^6\frac{V}{m})\\\sigma_{max}=3*10^{-5}\frac{C}{m^2}](https://tex.z-dn.net/?f=%5Csigma_%7Bmax%7D%3D%5Cepsilon_oE_%7Bbreakdown%7D%5C%5C%5Csigma_%7Bmax%7D%3D%288.85%2A10%5E%7B-12%7D%5Cfrac%7BC%5E2%7D%7BN%5Ccdot%20m%5E2%7D%29%283%2A10%5E6%5Cfrac%7BV%7D%7Bm%7D%29%5C%5C%5Csigma_%7Bmax%7D%3D3%2A10%5E%7B-5%7D%5Cfrac%7BC%7D%7Bm%5E2%7D)