Introduction
This experiment on saltwater and sound will help us to determine whether sound travels faster in different water salinities.
Our hypothesis is that the speed of sound gets slower as the salinity increases.
Aim
To determine the speed of sound in different salinity of the water.
Basic Building Concept
1. The salinity of the Arctic Ocean is 20 ppt.
2. The salinity of the Atlantic Ocean is 35 ppt.
3. The salinity of the Salton Sea is 44 ppt.
4. The salinity of Mono Lake is 87 ppt.
5. The salinity of the Dead Sea is 210 ppt.
Requirements
1. Water Sample
2. Transducer
Theory
1. Salinity of water is the amount of salt added to water. As the amount of salt increases, salinity also increases.
2. We have assumed that the speed of sound decreases with an increase in salinity.
Procedure
Step 1: Use the salinities of the Arctic Ocean (20 ppt), the Atlantic ocean and pacific ocean (35 ppt), the Salton sea (44 ppt), the Mono lake (87 ppt), and the Dead sea (210 ppt) for the experiment.
Here, ppt denotes Parts Per Thousand.
Step 2: With the help of two transducers, generate a signal of 4 hertz at one hundred thousand cycles per second.
Step 3: Measure the speed of the sound in water which is equal to the delay of sound between two transducers.
Observations
1. The speed of sound in water ranged from 1,488.1 m/sec to 1,718.4 m/sec in the salinity between 20 ppt and 210 ppt.
2. We have found that the higher the salinity in the water, the greater will be the speed of sound.
Result
The result obtained contradicts our hypothesis. As we thought that salt will be responsible for the speed of sound and as salinity increases, speed will decrease. But we find that the speed becomes faster as the salinity increases. And this happened due to density.
Precaution
1. Carefully measure the speed.
2. All the samples of water must have different salinity.
Conclusion
From our experiment, saltwater and sound, we found that as the salinity of water increases, the speed of sound gets faster.
VIVA Questions With Answers
Q.1 What was the aim of our experiment?
ANS. To determine the speed of sound in different salinity of the water.
Q.2 What was the hypothesis of this experiment?
ANS. Our hypothesis was that the speed of sound gets slower as the salinity increases.
Q.3 Was your hypothesis correct?
ANS. No, our assumption was wrong as we thought an increase in salinity decreases the speed of sound, but the experiment showed the inverse effect, maybe because of the density factor.
Q.4 What do you understand about salinity?
ANS. The salinity of the water is the amount of salt added to the water. As the amount of salt increases, salinity also increases.
Q.5 Why salinity occurs in water bodies?
ANS. This is caused by the collection of salt, over thousands of years from rainwater that can move under the groundwater and sometimes because of weathering of rocks.
Q.6 Name the quantity which measures salinity in water.
ANS. The salinity of the water is usually measured in grams of salt per liter (g/l) or grams of salt per kilogram of water (g/kg).
Saquib Siddiqui is a Mechanical Engineer and a content creator. He has special interest in science experiments and teaches the same to school and college students. He is also a technical lead at RUDE LABS PVT. LTD.
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