Experiment 2: Fluid Dynamics

The purpose of this experiment was to compare our experimental values for the rate of flow out of a bucket with those of our experimental values.

We began the experiment by filling a large bucket with water and then allowed water to flow out of a small hole drilled near the bottom of the bucket. We took 6 trials and measured how long it took for a specified volume of liquid to exit from the bottom of the bucket. The trials for the bucket to empty 1000mL are as follows. All measurements are in seconds and have an uncertainty of +/- 0.15.

Trial 1: 30.01
Trial 2: 29.35
Trial 3: 29.59
Trial 4: 29.39
Trial 5: 29.82
Trial 6: 29.38

We also measured the diameter of the bucket to be 0.25m, the are of the hole in the bucket to be .31669 cm^2 and the initial height of the water to be 0.124m.

Using these measurements we found the average time for the bucket to empty 1000mL to be 29.59 +/- 0.25 seconds. Giving us a flow velocity of 1.06m/s. However our theoretical velocity from Bernoulli's equation gives us a velocity of 1.559 m/s. This shows that the time for theoretical time for the bucket to empty 1000mL to be 20.24 seconds. This gives us and error of 40%. While the error for this experiment is very high, there were many unaccounted for errors or uncertainties in this experiment. First the diameter of the hole drilled in the bucket may not have been exact and any excess plastic left over from the drilling could have impeded the flow rate out of the bucket. This makes sense because the experimental flow rate was slower than the theoretical flow rate.

Experiment 1: Fluid Statics

The purpose of this lab was to measure the buoyant force of a metal cylinder experimentally. To do this we used three different methods and then compared them. We used the underwater weighing method, displaced fluid method, and the volume of object method.

In the Underwater Weighing Method we first used a force probe to measure the weight of the metal cylinder in air. Then we did the same thing except this time in water. Using our two recordings we determined that the buoyant force (B) could be expressed as B=mg-T. Using our calculated values of the weight and the tension of the string we found our buoyant force to be about 1.09 N.

In the Displaced Fluid Method we first began by measuring the mass of a dry beaker. Then we filled a graduated cylinder to capacity and lowered the metal cylinder into it. We collected the overflow from the graduated cylinder and weighed the mass of the overflowed water. We then applied Archimedes Principle which states that the weight of the displaced water is equal to the buoyant force. We then calculated this to be 1.04 N.

Lastly in the Volume of Object Method we took the diameter and height of the metal cylinder and calculated it's volume. We determined this to be 1.03*10^-5 m^3. This is also how much water the cylinder would displace. We know the density of water to be 1000 kg/m^3 so we used to density to calculate the weight of the water which would be equal to the buoyant force. We found this to be 1.03 N.