Calculate the height from the speed of sound

In summary, to find the depth of the well, the equation 1.63s = √2(h)/g + h/vs can be solved by taking the radical to one side and other terms to the other and squaring both sides or by setting y = √h, y2 = h and using the quadratic formula. The equation can then be simplified to 1/2gt² = vt₂ = v(1.63 - t), with only one unknown.
  • #1
Julio Cesar
5
0

Homework Statement


You drop a stone down a well. You hear the 'splash' 1.63s later. How deep is the well? The speed of sound in air is 343m/s.


Homework Equations


Kinematic equation: Δh=V0t+1/2gt2

Also, I've narrowed the problem down to the total time of 1.63s is equal to...
1) the time the stone leaves the hand and hits the water bellow. This is t1
2) The time it takes for the sound to rise from the water and be heard above. This is t2

So 1.63s = t1 + t2

The Attempt at a Solution



Now since the initial velocity is zero. We can just say that Δh=1/2gt12

And the speed of sound is v=meters/sec (since I want the distance I can call meters displacement.) Right?

So now I have two equations that I can rearange for time (t1 and t2

And I also have the full total time of Ttotal which is equal to the sum of t1 + t2

But my question is this...I need to find the displacement (or height) but I have three unknowns (both time values and the height) but I also have two equations. So my brilliant self did this...

1.63s = √2(h)/g + h/vs

I tried to solve for "h" and that ended horribly. So now I'm stuck. I know I can get this. I desperately want to solve this now to prove to myself that I am not stupid. So I've been stuck for over a few hours (taking breaks of course) and going over it in my head as to how to either find one of the time values or the height altogether.

Please if someone can just give me a little tip. I don't want the answer nor a plug and chug final equation. I just need a little math tip as to what to do next (or what am I doing wrong)...

Thanks for any and all help, ya'll.
 
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  • #2
You could solve that equation by taking the radical to one side, other terms to the other and squaring both sides. But the easier approach is to start with
distance down = distance up
1/2gt² = vt₂
1/2gt² = v(1.63 - t)
which has only one unknown.
 
  • #3
You have already done the hard part. Nice job! Now...

Let y = √h, y2 = h, and solve your equation using the quadratic formula.
 

FAQ: Calculate the height from the speed of sound

How is the speed of sound related to height?

The speed of sound is directly related to height. As the altitude increases, the speed of sound decreases due to the decrease in air density. This means that sound waves travel faster at sea level compared to higher altitudes.

What is the formula for calculating height from the speed of sound?

The formula for calculating height from the speed of sound is h = (c / (2 * f))^2, where h is the height, c is the speed of sound, and f is the frequency of the sound wave.

How does temperature affect the speed of sound and the calculation of height?

Temperature has a significant impact on the speed of sound and the resulting calculation of height. As temperature increases, the speed of sound also increases, meaning the height will be calculated as lower than it actually is. Similarly, a decrease in temperature will result in a slower speed of sound and a higher calculated height.

Can this calculation be used for all altitudes and sound frequencies?

While the formula for calculating height from the speed of sound can be applied to any altitude and sound frequency, it is most accurate for altitudes below 11,000 meters and frequencies between 20 Hz and 20,000 Hz.

Are there any other factors that can affect the accuracy of this calculation?

Yes, there are other factors that can affect the accuracy of this calculation. These include changes in air pressure, humidity, and wind speed, as well as the shape and composition of the surrounding terrain. These factors can all impact the speed of sound and ultimately affect the calculated height.

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