Physics, 19.06.2020 01:57 mistycascaden

A stationary sub uses sonar to send a 1.18x10^3 hertz sound wave through ocean water. The reflected sound wave from the flat ocean bottom is 324 meters below the sub is detected 0.425 seconds after it was sent from the submarine. Calculate the speed, v, wavelength and period of the sound wave

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Answer from: yushan2751

a) v = 1524.7 m/s

b) T = 8.47*10^-4 s

λ = 1.29 m

Explanation:

a) First, in order to calculate the speed of the sound wave, you take into account that the velocity is constant, then, you use the following formula:

$v=\frac{d}{t}$

d: distance traveled by the sound wave, which is twice the distance to the ocean bottom = 2*324 m = 648 m

t: time that sound wave takes to return to the sub = 0.425

$v=\frac{648m}{0.425s}=1524.7\frac{m}{s}$

hence, the speed of the sound wave is 1524.7 m/s

b) Next, with the value of the velocity of the wave you can calculate the wavelength of the wave, by using the following formula:

$v=\lambda f\\\\\lambda=\frac{v}{f}$

f: frequency = 1.18*10^3 Hz

$\lambda=\frac{1524.7m/s}{1.18*10^3s^{-1}}=1.29m$

And the period is:

$T=\frac{1}{f}=\frac{1}{1.18*10^3s^{-1}}=8.47*10^{-4}s$

hence, the wavelength and period of the sound wave is, respectively, 1.29m and 8.47*10^-4 s

Answer from: Quest

most voltage drop calculators want the distance between the source and destination. then internally, they double it so both the source and return wires are calculated. but you need to know which distance the calculator uses so you're not half of what you should be or double what you should be.

most circuit breakers will not take a #6 directly, so the electrician will have to splice on a smaller pigtail. you also have to upsize the grounding wire when you upsized the ungrounded (hot) wire (see note in 250.122). this will preclude using most cable assemblies, as a cable with #6 copper will most likely only have a #10 grounding conductor. you need a #6 grounding conductor if the circuit is 20a. a #8 cable is no better, as it will have a #10 grounding conductor too. but most 20a breakers will take a #8 directly.

in your related post, you didn't say what type of load this is. if it is a light or heater, voltage drop won't be a big issue. if this is a motor, the current needs are huge at startup and the voltage drop can pose a problem. if this is a motor, knowing if the motor is under much load during startup will answer the voltage drop effect (a saw is easier to start than a compressor).

Answer from: Quest

true

explanation: