4. Discussion

4. Discussion

4.1 Key Findings, Comparison and explanations

From the data collected, a drop of pressure in water can be seen in the results. The height of the water in each straw decreases as the distance increases. The height of the water in the straws is equal to the amount of excess pressure in the water. Hence, we were able to see the significant decrease of excess pressure in the water through the water level drop throughout the 6 straws. To ensure that the results were more visible to compare the height differences in the amount of water in each straw, we decided to film the experiment with a solid grey background, along with adding brown food colouring to the water used in the set-up.

Another experiment we have found was on water pressure at depth from Edication.com, which explains to us what atmospheric pressure is and how it affects us, examples are swimming and scuba-diving. However, this experiment does not show us the difference between the increase or decrease in the distance of the water source to the opening. Our experiment has a larger number of data compared to this experiment, hence, it is more accurate, and reliable. (Education.com, 2013)

As shown from the results, we can conclude that as the distance from the water source increases, the pressure in the water decreases. Hence there was a noticeable drop in the height of the water in the straw.

The distance range increased consistently from 17.3 cm to 88.3 cm, the average height of the water decreased from 31.15 cm to 0 cm.

The results have shown that there would be a higher water pressure if the straws were closer to the water source compared to the straws that are further away from the container. This experiment allows us to know that there would be a decrease in the pressure as the distance from the water source to the pipe increases.

This ties with Bernoulli’s equation because it explains the relationship between pressure, gravitational potential energy and kinetic energy in water distribution systems. Bernoulli’s equations state where points 1 and 2 lie on a streamline, the fluid has a constant density, the flow is steady and there is no friction.

This experiment addresses some of the UN 17 Sustainable Development Goals, clean water and sanitation, affordable and clean energy, as well as sustainable cities and communities.

4.2 Limitations and Recommendations

Due to time restrictions, we could not get a heat shrink wrap; hence we had to replace it with duct tape to connect the water dispenser bottle and the pipe connector. The lack of the heat wrap caused some water leakage, which might cause the experiment to be less accurate because the decrease in water would cause the height of water level to drop.

Another problem is the presence of the air bubbles, causing the height of water in the straw to be inconsistent. The air enters through the air spaces, resulting in the overwhelming amount of air bubbles in the straws, causing inaccurate results. We have come up with different solutions as to why there were a lot of air bubbles in the straws, such as shaking the tube filled with a little bit of water then carrying on with the experiment to reduce the trapped air bubbles, but it failed.

The last problem we had was measuring the height of the water in the straws. This was a problem because the air bubbles added to the height of the water, so it was difficult to measure the height of the water only. So, we had to measure the total height of the water with the air bubbles minus the height of the air bubbles to find the final answer. However, the answers might differ.

4.3 Evaluation of Hypothesis

The hypothesis presented that the height of the water in each straw and the horizontal distance decrease linearly. However, the experiment proved the hypothesis to be inaccurate and incorrect. The results of the experiment showed that there was a bell curve drop in the results, unlike our hypothesis that we have predicted. The distance range increased consistently from 17.3 cm to 88.3 cm, the average height of the water decreased from 31.15 cm to 0 cm. Hence there was a noticeable drop in the height of the water in the straw.