How long does it take for the sound to travel a known distance in a well?

[Confusedkid34]

Homework Statement

How deep is the well? Drop a stone and I took 16s to hit the ground level.

The air temperature is 20 degrees.

Acceleration is 9.8 m/s squared.

M=1kg

V1=0 m/s

Speed of sound= 343.8m/s squared
Find how deep the well is.

Homework Equations

D=t/v

I don't really know at all

Speed of sound.

The Attempt at a Solution

No ideas.

 

[SammyS]

Homework Statement

How deep is the well? Drop a stone and I took 16s to hit the ground level.

The air temperature is 20 degrees.

Acceleration is 9.8 m/s squared.

M=1kg

V1=0 m/s

Speed of sound= 343.8m/s squared
Find how deep the well is.

Homework Equations

D=t/v

I don't really know at all

Speed of sound.

The Attempt at a Solution

No ideas.

Hello Confusedkid34. Welcome to PF!

Your obviously missing some words in your problem statement. What is it that takes 16 seconds to hit the ground?

To make all this clearer, please state the problem word for word as it was given to you.

 

[gneill]

Homework Statement

How deep is the well? Drop a stone and I took 16s to hit the ground level.

The air temperature is 20 degrees.

Acceleration is 9.8 m/s squared.

M=1kg

V1=0 m/s

Speed of sound= 343.8m/s squared
Find how deep the well is.

Homework Equations

D=t/v

I don't really know at all

Speed of sound.

The Attempt at a Solution

No ideas.

Unless there's more to the problem statement than you've posted, only some of the given information is relevant.

Does the stone have a constant speed as it falls, or does it accelerate? What formula applies?

 

[Confusedkid34]

The speed is constant, it takes 16s to hear the Rock hit the bottom.

So 16s for the rock to hit the bottom and for the noise to travel back.

It starts at rest. Both the sound and rock travel the same distance.

Speed of sound is 343.8 m/s

So time equals 16s. t=t1+t2

T1= time for the stone to hit the ground.

T2= time for sound to travel back.

So we need to solve for d. By finding out what t1 and t2 are.

 

[SammyS]

The speed of sound is constant, it takes 16s to hear the Rock hit the bottom.

So 16s for the rock to hit the bottom and for the noise to travel back.

It starts at rest. Both the sound and rock travel the same distance.

Speed of sound is 343.8 m/s

So time equals 16s. t=t1+t2

T1= time for the stone to hit the ground.

T2= time for sound to travel back.

So we need to solve for d. By finding out what t1 and t2 are.

How far does sound travel in a time of t₂ ?

How far does the rock fall in a time of t₁ ?

If t₁ + t₂ = 16, then express t₂ in terms of t₁ .

Put all of that together, solving for t₁.

 

[Confusedkid34]

The distance for t1 and t2 are the same.

But I don't understand how to do that?

Somewhere do I have to apply this in a quadratic ?

 

[gneill]

The speed is constant, it takes 16s to hear the Rock hit the bottom.

So 16s for the rock to hit the bottom and for the noise to travel back.

What happened to gravity? Your problem statement didn't mention anything about hearing the rock hit the bottom, only that it took 16 second to hit the bottom, no sound involved.

So really your problem statement should go something like:

An observer drops a stone from rest into a deep well. The stone falls under the influence of gravity. 16 seconds after the stone begins its fall the observer hears the sound of the rock hitting the bottom. How deep is the well?

It starts at rest. Both the sound and rock travel the same distance.

Speed of sound is 343.8 m/s

So time equals 16s. t=t1+t2

T1= time for the stone to hit the ground.

T2= time for sound to travel back.

So we need to solve for d. By finding out what t1 and t2 are.

Sounds like a plan. Can you write the expressions for each time?

 

[SammyS]

The distance for t1 and t2 are the same.

But I don't understand how to do that?

Somewhere do I have to apply this in a quadratic ?

Please use the QUOTE button to indicate which post you are relying to.

It will help a lot.

I'll do this post, then let gneill finish up. (If he's willing.)

You didn't answer those questions I asked in post #5 .

Answering them will help significantly in solving this problem.

 

[Confusedkid34]

Your right. I didn't include all the information.

So we need an equation to solve for d. As well we need to figure out t1 and t2.

I have no idea how to do this and I could use some guidance.

 

[gneill]

Your right. I didn't include all the information.

So we need an equation to solve for d. As well we need to figure out t1 and t2.

I have no idea how to do this and I could use some guidance.

Suppose you happened to know the distance d. How would you write an expression for the amount of time, call it t2, it takes for the sound to travel that far?