Buoyancy and Displacement
Ships do not sink because of displacement; the ship moves more water than the ship actually weighs.
Archimedes Principle: Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.
Density is mass of a unit volume of a material substance, expressed as kilograms per cubic meter in MKS or SI units. Density offers a convenient means of obtaining the mass of a body from its volume or vice versa; the mass is equal to the volume multiplied by the density, while the volume is equal to the mass divided by the density. The weight of a body, which is usually of more practical interest than its mass, can be obtained by multiplying the mass by the acceleration of gravity. Tables that list the weight per unit volume of substances are also available; this quantity has various titles, such as weight density, specific weight, or unit weight. D = mass/volume
Displacement is distance moved by a particle or body in a specific direction. It is a vector quantity, possessing both magnitude and direction. The distance traveled by the point depends on the path that it follows; it will be equal to the magnitude of the displacement only if the path is straight. In mechanics, it is frequently necessary to distinguish between the distance that a point moves–or through which a force acts–and the displacement of the point or the force.
The purpose of this experiment was to make an object buoyant by adding a sufficient amount of extra volume to displace the water necessary.
My hypothesis was that the additional amount of displacement needed would be .54 liters. The needed amount of displacement was found by first finding the difference between the mass and displacement. The solution was the difference in mass and the weight of the water being moved. This solution was divided by the density of the salt water at Seaquarium, which was 1.03 kilograms.
The materials that were needed to conduct this experiment was a concrete or lead object, a scale to weigh the object, string, empty bottles, sea water, a graduated cylinder for measuring the water accurately, and buckets filled with sea water.
The procedure followed to perform the experimentation is as follows:
1. Choose a concrete or lead object and weigh it on a scale. The unit of the scale was pounds. It s mass was 2.7 pounds.
2. To find the weight of the object in ounces, the whole number of the weight was multiplied by 16 and then add the decimal. Then the solution was divided by 16. To convert the weight from ounces to kilograms, 2.44 was divided by 2.2.
i. 2 x 16 = 32
ii. 32 + 7 = 39
iii. 39/16 = 2.44
iv. 2.44/2.2 = 1.1
3. To obtain the volume of the object, a bucket was filled with sea water .The inside of the bucket was marked with a marker where the water reached. Then the object was placed into to the bucket to see how much the water would rise. When the object was taken out, the water height reduced.
4. Using a graduated cylinder in liters, we measured how much water it took to reach the original point. This is the volume of the object. We converted it into liters by dividing by 1000.
5. Displacement was calculated by multiplying the object’s volume by the density of the seawater. .65 x 1.03 = .6695 Liters
To find the extra amount of displacement needed was found by finding the difference between the mass and displacement. The solution was the difference in mass and the weight of the water being moved. This solution was divided by the density of the salt water at Seaquarium, which was 1.03 kilograms. The extra displacement needed was .54 liters of water, which was added to a 1-liter bottle.
6. The object was tested by putting it in the ocean to see if it floats.
7. Recalculated the air needed to make the object float. Added and subtracted water.
The result of the experiment was that the object actually needed 4.39 liters of water to float in the seawater. We also used a bigger bottle.
In conclusion, the hypothesis was incorrect. 4.39 Liters of water were necessary to make the object buoyant. The percentage error from our hypothesis was 45%.
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