Joslin
Posts: 2
Joined: Sun Sep 08, 2019 12:20 pm
Occupation: Parent

### kerplunk theory

When I was a kid my dad told me you could figure out the relative depth of the water of a pond by dropping two like sized rocks in and that the higher the pitch kerplunk would tell you it was shallower than the deeper pitched kerplunk. Wondering if there is any science to back this up?
Thanks,
Joslin

ordeluca
Student Expert
Posts: 3
Joined: Tue Aug 20, 2019 6:26 pm
Occupation: Student

### Re: kerplunk theory

Hello Joslin,

No, the depth of the pond would not affect the pitch of the kerplunk. The kerplunk sound comes from the rock creating air bubbles as it sinks through the water, these bubbles splitting apart, "popping", and water filling in the gaps. The pitch of the kerplunk is affected by the size of the air bubbles, which isn't affected by the depth of the pond.

Is this question related to a science project? If so, what is your hypothesis, is it that the depth of the water affects the pitch of the kerplunk? If that isn't your hypothesis, some others that might be interesting are the effect of the size of the rock, or salinity of the water on the pitch of the kerplunk.

I hope this helps,
Owen

Joslin
Posts: 2
Joined: Sun Sep 08, 2019 12:20 pm
Occupation: Parent

### Re: kerplunk theory

Thanks so much! I appreciate the help! We were talking about sonar and other ways to figure out depth. Thanks again, Joslin

324B21
Expert
Posts: 67
Joined: Wed Sep 02, 2015 12:49 pm
Occupation: Student -- College

### Re: kerplunk theory

Hey Joslin,

I came across this post, and thought of another way you could figure out depth using a rock. You drop the rock into the water and time how long it takes to reach the bottom.

Here is a great link that explains how that would work.https://www.quora.com/How-do-you-determine-the-formula-to-calculate-depth

I am so excited to see you thinking of ways to measure depth. If you need any further assistance, please feel free to come back and ask!

Evan