Archimedes’s Principle
1. Weight = mass x 9.80 g/cm^3
W= 45g x 9.80 N
W= 44,100 dynes
2. Buoyant force (calculated) = weight in air – weight in water
BF = 44,100 dynes – 38710 dynes
BF = 5390 dynes
3. Volume of Water = radius^2 x length
V= (.63cm) (4.65cm)
V= 5.80 cm
4. Buoyant force (measured) = mass in air/ density
BF= (44,100 g) / (7.76 g/cm^3)
BF= 5684 cm^3
5. % difference = BF calculated – BF measured/ BF measured
% difference = 5390 – 5684 / 5684
% difference = 5.4 %
6. Density = Mass / Volume
Density = 45 g / 5.80 cm^3
Density = 7.76 g/cm^3
7. Volume of wood = length x width x height
V = (7.62cm) (7.63cm) (3.86 cm)
V = 224. 42 cm^3
Questions
2.) Because an overweight person displaces more fluid when stepping into a pool. By displacing more fluid, the person creates a greater buoyant force making it easier for him to swim.
5.c) By placing a battery into the water with a floating rod into its deep cylindrical cavity it is quite easy to determine the condition of the battery. The diluted battery will have a much higher density than that of a highly charged battery. From the observation of how the battery floats you can tell its condition.
8.) We were able to find the volume of displace water in Part II quite easily. First we placed a large tupperware container on the table and in it a smaller container filled to the top with water. When the block of wood was placed in the container, water fell out of the smaller container into the larger container. By placing the water which fell out of the smaller container into a cylinder, you are able to measure the volume of displaced water.
9.) No I did not use Archimedes’s principal to find the densities. I used the density formula of dividing the mass by the volume. We find the densities and compare them to the densities of water to help understand the mechanics of buoyant force.
Discussion
In part two of the lab dealing with Archimedes’s principle, we were comparing the buoyant force of a block of wood to its weight in dynes. The first step of the operation dealt with measuring the quantity of displaced water. We did this using two containers, one small and one large, and filled the small container to the brim with water. By placing the block of wood in the small container and using a graduated cylinder, we were able to find the amount of water displaced by the block.
Furthermore, using a graduated cylinder with markings below the 100 mL line would have allowed for more accurate measurements of the initial volume of air in the graduated cylinder.
3. The beaker was filled with water and the metal was placed in the water.
For part C, the concentration of was determined to be 1.01 mol/L, 0.973 mol/L, and 1.158 mol/L. These results show a relatively closed to the accepted 1.00mol/L of NaOH. The differences of these results are understandable since the concentration of NaOH would changes over time because during the transfer of NaOH powder in part A, it was exposed to the air, thus it could reacts with CO2 in the atmosphere to produce Na2CO3 and water, therefore, changing the concentration of NaOH. Furthermore, the NaOH could also react with the glass thus it wills also reducing its concentration. However, all of the concentration of NaOH that was determine are maximum of 0.158mol/L differences compare to the standard 1.00 mol/L, therefore, it can be concluded that the result are accurate.
Archimedes principle says that the magnitude of the buoyant force always equals the weight of the fluid displaced by the object. This buoyant force always acts upward through the point that was the center of gravity of the displaced fluid. In the case of floating objects the buoyant force is equal to the force of gravity on the object. Knowing that the change in pressure is equal to the Buoyant force per unit area (ΔP = B/A) we see that B = (ΔP)A and ΔP = ρgH where ρ is the density of the fluid g is the acceleration due to gravity and H is the height of the fluid displaced.
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.
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Placed 30 mL of water within a beaker and placed the metal sample within the beaker. After placing the metal sample within with beaker the volume of water in the beaker changed. The volume change was recorded for the volume of the metal sample.
The purpose of this lab is to determine the density of a solid and an unknown liquid in order to determine the unknowns from a list of substances provided in the lab instruction. A method to identify the substance is to figure out the density (d=m/v) where d is the density equals to the mass divided by the volume of the substance. When measuring the mass, reset the balance to zero to obtain only the mass of the object in grams (g) and not anything else. When measuring the volume, read at the meniscus for an accurate measurement.
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The flask was then taken back to the first lab bench and placed under the buret with sodium hydroxide. The initial volume of the base in the buret was
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