Science Fair on How Objects Float

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February 21, 2013
Physics

How much salt does it take for an object to float?

Table Of contents

Page2 - Abstract
Page 3- Introduction/ Research
Page 4- Purpose/ Hypothesis
Page 5-Materials
Page 6- Procedure
Page 7- Data/ Observations
Page 8- Conclusion
Page 9- Acknowledgements
Page 10-Biblical Application
Page 11- Sources
Pages 12 and 13-Log Book

Page 1

Abstract

My project is about how much salt it will take for objects to float. In my project I will explain why certain objects float while others sink. I took three different objects with different amount of density and put them each in ten cups of water. I then put in teaspoons of water and recorded whether or not the objects floated until all the objects were floating. I was able to see how an objects density affects how much salt is needed to make it float.

Page 2
Introduction/ Research

When trying to make an object float it depends on its density. Density is the “mass per unit volume.”[7] An object floats if it has less density then water. Objects like a boat floats because it has many parts that are filled with things that are less dense then water like air. When you add salt to the water the water becomes more dense allowing different objects to float. The salt dissolves into ions Na+ and Cl- which increases the mass of the water. The ions then link with the water molecules and then the molecules have a greater mass then the oxygen and hydrogen that the water is made of. Density is mass divided by volume and since there is now more mass the density of the water has also increased. The object does not have to be lighter than the water it just has to have a bigger ratio of empty space to mass than the water. For an object to float it has to be positively buoyant.” Buoyancy is an upward force exerted by a fluid that opposes the weight of an immersed object.” [6] When an object it positively buoyant its buoyant force is high enough to go against gravity and float. If the object is negatively buoyant it will sink. This is because gravity will be forcing it down until it reaches the bottom. If an object is neutrally buoyant it will not sink or float. The buoyancy and gravity are equal in this case. An object that is neutrally buoyant can be kept in one position or be moved in water.

Page 3
Purpose/ Hypothesis

The purpose of my project was to show why come objects float when others sink. My project showed that it does not matter how big an object is on whether or not it floats but on how much density the object has. My hypothesis is: if an object has more density than the water it will then sink.

Page 4
Materials

1. Egg
2. Measuring cup
3. Tub ( area of tub is 113.04)
4. Water
5. Toy car
6. Sea Salt
7. Teaspoon

Page 5
Procedure

Step 1- Fill up a tub with ten cups of water.
Step 2- Then put a toy car, and egg, and a paper clip in the water which are the controls in this experiment. The salt is the variable because the amount is changed. Step 3- Put the objects in the water and begin to add sea salt into the water. Step 4- Measure the salt out into a teaspoon and pour it into the water. Step 5- Wait a minute and record what happened to the objects. Step 6- Do this until each object is floating in the water.

Page 6
Data/Observations

Page 7
Conclusion

My experiment was about how the buoyancy of an object affects whether or not the object floats and how much salt it will take for the object to float. My hypothesis was that it would take more salt if the object has more density. The toy car took more salt to float because it had the most density out of all of the objects. When you add salt to the water the water becomes more dense allowing different objects to float. Density is mass divided by volume and since there is now more mass the density of the water has also increased. If I had more time for this project would test this with different temperatures of water and...
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