Sound Waves dropping a rock into a well

In summary, the rock falls faster than the sound waves and therefore the distance it falls is shorter than the time it takes the sound waves to travel back up the well.
  • #1
newfie88
6
0

Homework Statement



When you drop a rock into a well, you hear the splash 1.5 sec later. How deep is the well?

Homework Equations





The Attempt at a Solution


Speed of sound 343m/s
x=(343m/s)(1.5)=514.5
 
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  • #2
No. The 1.5 seconds is the time it takes the rock to drop to the water plus the time it takes the sound to come back up the well to your ear.

Try again.
 
  • #3
do i need to take half of the time...Also is the answer 11 m.
 
  • #4
newfie88 said:
do i need to take half of the time...Also is the answer 11 m.

No. The rock doesn't fall at the same speed that the sound wave travels. The time for each direction will not be equal.

Break it up into two parts. You can express the distance the rock falls in terms of the time it takes to reach the water (call that t1). Then express the distance in terms of the velocity of the sound wave as it goes back up the well (call that time t2).

You were given the total time, so you can relate these equations to each other.
 
  • #5
Im sorry i don't really get this whole physics thing...does gravity have anything to do with this question...and the answer in back of the book is 11 m but no matter what i do icant seem to get that answer
 
  • #6
newfie88 said:
Im sorry i don't really get this whole physics thing...does gravity have anything to do with this question...and the answer in back of the book is 11 m but no matter what i do icant seem to get that answer

Yes gravity is involved because the rock is falling vertically.
Start by doing this: Look up your kinematic equations. Show me the equation for distance (y, say) in terms of g, and t1 (the time it takes the rock to fall the distance y). You know the initial velocity of the rock is zero.

If you show your work I can more easily point out what you are doing wrong.
 

1. What happens to sound waves when a rock is dropped into a well?

When a rock is dropped into a well, it creates a disturbance in the water which causes sound waves to travel through the water and to the surface of the well.

2. How do sound waves travel through water?

Sound waves travel through water in a similar way to how they travel through air, by creating vibrations. However, sound waves actually travel faster and farther in water due to its higher density compared to air.

3. Why does the sound of a rock dropping into a well become fainter as it travels through water?

The sound of a rock dropping into a well becomes fainter as it travels through water because water is a denser medium than air. As sound waves move through the denser medium, they lose energy and become quieter.

4. Can sound waves travel through all types of materials?

Yes, sound waves can travel through all types of materials, including solids, liquids, and gases. However, the speed and distance that sound travels can vary depending on the density and properties of the material.

5. How do sound waves behave when they reach the surface of the well?

When sound waves reach the surface of the well, they are reflected back into the water and can continue to travel through the water until they reach the edges of the well or are absorbed by the well walls. This is known as an echo and is commonly heard when a sound is made in a confined space, such as a well.

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