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PURPOSE
The purpose of this experiment was to determine how much the hydrodynamic
shape and mass of an object would affect its velocity when sinking through
water.
I became interested in this idea when watching a Discovery Channel documentary
on submarines, which must be able to travel through water at high speeds.
The information gained from this experiment can be used to help create
new and modified hull shapes for submarines and boats so they can travel
more quickly and more efficiently. This will also help architects
to design new bridge support columns that will let water flow around them
more easily.
HYPOTHESIS
My first hypothesis is that a shape with heavier mass will sink at a
faster weight than that of a lighter weight in the water tube.
My second hypothesis that that a shape with more streamlined hydrodynamic
properties will sink at a faster rate in a water tube.
I base my hypothesis on the physics of aerodynamics and hydrodynamics
that say that a more smooth and streamlined shape will be like a wing shape
and let more water flow past them easier
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Experiment Design
The constants in this study were: Same mass in the shapes, same distance
to travel, same amount of pressure when it is dropped, same dropper, same
water tube.
The manipulated variables were the different shapes of the objects and
the mass of each shape.
The responding variable was the speed the objects traveled through the
tube.
To measure the responding variable I will have someone drop the object
on the count of three and I will start the stopwatch, then stop it again
when I hear it hit the bottom of the tube.
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MATERIALS
| QUANTITY |
DESCRIPTION |
| 1 |
foot clear plastic tube
(One end closed off) |
| 1 |
person to drop |
| 4 |
wood spheres |
| 4 |
wood cones |
| 4 |
wood cylinders |
| 4 |
wood cubes |
| 1 |
stopwatch |
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PROCEDURES
1.Make 4 pyramids, 4 spheres,4 cubes and 4 cylinders.
2.Drill the core out of each shape.
3.Fill one of each shape with 30 grams of shot (shotgun shot).
4.Fill one of each shape with 60 grams of shot.
5.Fill one of each shape with 120 grams of shot.
6.Fill one of each shape with 200 grams of shot.
7.Fill all holes with same amount of glue to seal the hole.
8.Fill the tube with water almost to the top.
9.Drop all of the 30 gram shapes one at a time.
10.Record the data.
11.Drop all of the 60 gram shapes one at a time.
12.Record the data.
13.Drop all of the 120 gram shapes one at a time.
14.Record the data.
15. Drop all of the 200-gram shapes one at a time.
16.Record final data.
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Results
The original purpose of this experiment was to determine if the shape
and mass of an object would affect its freefall through water.
The results of the experiment were that the more streamlined an object
is, the faster of rate it will fall through water. The cone fell
the fastest because it is streamlined, the cylinder fell the slowest and
the cube and spherical shape fell somewhere in between those two. See the
table and graph below
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CONCLUSION
My first hypothesis was that a shape with a more streamlined hull
shape would sink faster in a water tube.
My second hypothesis was that a shape with more mass would sink faster
that a shape with less mass.
The results indicate that this hypothesis should be accepted because
the cone sunk at the fastest rate and was the most streamlined shape.
Because of the results of this experiment, I wonder if an object with
a larger surface area could ever fall faster that a streamlined shape.
This may seem impossible unless the larger object has much more mass than
the streamlined shape.
If I were to conduct this project again I would use better shapes for
the experiment and use a better water tube than this last time. I
would try to find a clear tube to drop the shapes into and I would use
a more accurate form of measurement.
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RESEARCH REPORT
INTRODUCTION
Have you ever wondered about how submarines dive and surface that easily?
They are so big and lunky that you would think they would sink to the ocean
floor and not be able to surface again. If you read this report,
you will find out how submarines sink and surface among other things.
SUBMARINES
Submarines are submersible warships used for surprise attacks.
The first submarine plans were made in 1578 by William bourne. These
were the first practical submersibles. Submarine designs have been
changed many times to many different shapes. (See submarine design)
They rise and sink using ballast tanks that they fill to the top with water
to sink and empty them to rise.
VELOCITY
Velocity is the speed in which an object is moving in a given direction.
Velocity is shown in time and distance as in miles per hour, meters per
hour,etc. There are two types of velocity, uniform velocity, which
means that the distance and the direction traveling are same throughout
the whole motion. Velocity may by variable, which means that the
distance and the direction are unequal.
HISTORY OF SUBMARINES
The very first working submarine was a rowboat with waterproof
hides strapped to the top of it. The constructor’s name was Cornelius
van Drebbel. He demonstrated his invention invention in 1620, many
other attempts to perfect the submarine were made, and only few were excepted.
DESIGN OF SUBMARINES
The design of submarines was changed to travel faster. They
are now a cigar or teardrop shape. This makes them move faster and
dive deeper because it reduces the water resistance. Also, they are
built wider and can resist more pressure pushing in on them. This enables
them to dive to unbelievably deep levels of water.
SUMMARY
You have learned this much about submarines and velocity and
you might what to continue the research here. This will enable you
to learn more about them.
BIBLIOGRAPHY
1.Encarta, " velocity" Encarta 98, 1998
2.Lucille b. Garmon, Ph.D., "velocity" World Book Encyclopedia, 1999
3."Submarines"World Book Encyclopedia, 1991
4."Submarines"Encarta, 1999
5."Submarines" ,Discovery Channel
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