Experiment 2: Fluid Dynamics

The purpose of this experiment was to use Bernouli's Equation to calculate the time to empty a certain volume of a fluid.

We used a bucket with a whole at the bottom. We filled it up to a certain height and measured it. We the uncovered the initially covered whole and let 200 mL of water flow out of the bucket, while recording the time.

These were the measured times for 200mL to flow out of the bucket:

The measured values during the experiment were:

Volume emptied: 200 ± 10 mL

Height of the water: 13.6 ± 0.1 cm

Diameter of the hole: 0.60 ± 0.1 cm

We then calculated the theoretical time to empty 200mL:

We then calculated the percent error of the time to drain 200mL using the equation from above and tabulated the results:

Assuming that the diameter we measured was wrong, we calculated the "actual diameter" of the whole.  I used the average time to drain from the experiment results:

Conclusion:

When I compared the theoretical value to the experimental value, it did not agree with the uncertainty. The experimental time to drain the fluid was almost twice that of the theoretical value. None of the experimental values agreed with the theoretical value of 4.33 ± 1.69 seconds. Although the experimental values were not accurate, they were precise because the values were all within a second. This large experimental error must have come from the reaction time of the person taking time to start the timer when starting the experiment and the person telling the time taker to stop the timer. Another source of error was that the dh of the bucket as the water drained. We assumed the dh to be negligible compared to the height of the water in the bucket. Our percent error in the drill bit's diameter was 36.7%.  

Experiment 1: Fluid Statics

The purpose of Experiment 1: Fluid Statics was to find the buoyant force three ways and to find which one was more precise.

One was the underwater method where we found the buoyant force using the free body diagram. We measured the weight of the object in the air and submerged in water.

The second was the buoyant force by finding the amount of fluid that the object displaced. We initially measured the weight of the beaker alone when the was filled with water that overflowed when the object dispersed water of its container into the beaker. With a simple calculation, we found the mass of the water displaced. The weight of the displaced water was the buoyant force that acted on the object.

 The third way that we found the buoyant force was by measuring the volume of object. When we found the volume of the object, we knew that the volume of the object is the same as the volume of water that was going to be displaced by it. Once we found the weight of the displaced water, according to Archimede's Principal it was equal to the buoyant force.

Conclusion:
There were many sources of error in this experiment. In the first part, the LoggerPro force measurer could have not been properly calibrated and the string that the object was held with was not a mass-less string. In the second part of the experiment, a possible source of error could have been that the beaker was not one hundred percent full in the overflow spout. Another error for part two could have been that the object could have caused too much of a disturbance when the object was placed in the water making more water overflow. For the third experiment, there could have been possible source of error when the caliper was used to take measurement of the object's dimensions. Since all the obtained forces of buoyancy agree within the boundary of uncertainty, the values that we got are the same within the error uncertainty. I believe that the third method was the most accurate because it is the one with the least error and there was less propagation of error because there were only two measurements taken. If the cylinder would have been touching the bottom of the water container, it wouldn't have changed the buoyancy force because we calculate the buoyancy force using the volume of the fluid that it displaces. This doesn't depend on the depth that the object is submerged in as long as it is completely submerged.