Water Pressure vs Height, Lab Report Example

Introduction

As water fills a container, the water finds a horizontal surface where the pressure is constant. A free water surface can be open to atmospheric pressure and other pressure that are exerted within the container of the water in a closed type of vessel.  In an open container, the water surface in contact with the earth’s atmosphere has to deal with atmospheric pressure. Atmospheric pressure is equal to around 10.33- meters of water at sea level. In addition, any object located beneath the surface of water would also be subjected to pressures greater than the atmospheric pressure.

There are different types of pressure measurements, such as Absolute pressure, differential pressure, and gauge pressure. In this experiment, absolute pressure was examined.  Absolute pressure is measured in relation to a vacuum, such as atmospheric pressure.  The common unit of measure for atmospheric pressure is pounds per square inch absolute or psia; however, in this laboratory, atmospheric pressure is expressed in Kilo pascals (kPa). Pressure can be measured through the use of mechanical elements, such as motion sensors. The basic method is converting pressure to the physical motion. The movement is then transformed to obtain an output or pressure number. Motion sensors convert the motion into a signal.  As seen in Figure 1., there are three elements that are applied to detecting pressure through a sensing device. These elements include the sensing element, transduction element and signal condition. Figure 2, illustrates the basic mechanics and set-up of a sensory device for detecting water pressure in containers or tubes.  (Bicking)

Pressure is related to depth and examples are diving as used a good example.  It is commonly understood that as one dives to greater depths, the pressure in the eardrums becomes greater. Measurements have been illustrated to show the differences in pressure versus depth.  As seen in Figure 3, the pressure at different depths is compared to the force of fluid leaving  a tank.  As observed, pressure increases with depth.  In the current experiment, water pressure was examined using a motion sensor.  It was hypothesized that as the height of the water column in a tube increased, the water pressure would also increase.  The experiment used height as the independent variable and pressure as the dependent variable.  The tube size did not change, and served as the control for the experiment.

Materials and Methods

The experiment used a motion sensor in order to determine the water pressure of water height in a given tube. The  “Name of motion sensor” was provided by the instructor and placed on a s.  A “type of tube”  tube was used to determine the height of the water using a ruler.   In addition, the diameter of the tube was measured using a ruler and measured at 7.7 cm. The height of the water column was set at 5, 10, 15, 20, 25, and 30 cm for the experiment. The same tube was used for each trial; therefore, the diameter of the tube remained constant.  Four trials were conducted at each water height level. A ruler was used to determine the water level height was the same for each trial.  The motion sensor was used to determine the water pressure.  All results were recorded and the raw data was placed into Table 1.  The resulting data was analyzed using averages and standard deviations.  The data was plotted as a scatter plat graph using Microsoft Excel and a linear regression was conducted.  The linear equation and R2 value was illustrated on the graph.

Results

The results of the experiment are displayed in Table 1 and Table.  Table 1 includes the raw data for each Trial for all water level heights.  The results indicate that as water level increased in height (cm), the water pressure increased.  As seen in Table 2, the average water pressure at a height of 5 cm was 101.6 kPa compared to the average water pressure at a water level height of 30 cm at 103.9 kPa.  In addition, the water pressure increases with increasing height, as seen in Figure 4. Figure 4 displays the average water pressure versus height of the water level in tube.  In addition, the standard deviations were low, under 1 for each trial. Furthermore, a linear regression of the data is displayed in Figure 4 as well.  The linear equation and the R value are illustrated on the  graph, as well as the standard deviations.  (Figure 4).

Conclusion

The results of the study support the initial hypothesis that as water level increases, water pressure increases.  In addition, the initial review of the raw data clearly shows an increase in water pressure as water level is increased from 5 cm to 30 cm.  Further statistical evaluation, such as averages for each trial and standard deviations also show an increase in water pressure with water column height.  A scatter plot graph of the data clearly illustrates a linear line.  In addition, the R²value for the line was 0.997.  This value supports the results as a straight line, therefore supporting the hypothesis that as water level increases, water pressure increases.

The results of the standard deviations also show that each trial was conducted in the correct manner and resulted in the same data or close data.  The standard deviations did not fluctuate over 1.  In fact, the standard deviations were as low as 0.05.  This indicates that the averages for those water pressures were + or – 0.05.  In addition, the linear graph illustrates a straight line through the data point, clearly indicating that there is a an increase in x (water pressure) with an increase in y (height).

Water pressure increases with height and this can be due to weight.  The more weight in the water column, the more pressure that is exerted.  This type of information is important for many different types of industries, such as industries that use water tanks.  Understanding the pressure concepts is helpful in determining the amount of pressure in a tank.  The current experiment illustrated the changes that water pressure undergoes, with slight increases in water level.  Other factors, such as temperature and humidity were not analyzed in the experiment.  These factors could change pressure results due to precipitation.  Future studies should incorporate other factors in order to evaluate any fluctuations in water pressure.

Table 1.  Raw Data Collection of Water pressure (KPa)  versus Water height in tube (cm). 

Table 2.  Average Water Pressure (KPa) and Standard Deviation at different water level heights.

Works Cited

Biking, R.  Fundamentals of Pressure Sensor Technology.  (1998). Sensors. Retrieved from: http://www.sensorsmag.com/sensors/pressure/fundamentals-pressure-sensor-technology-846.

Pearson.  Chapter 2.  Water Pressure and Pressure Forces.  (2002). Prentice-Hall, Inc. A Pearson Company. pgs. 14-50.  Retrieved from: http://www.pearsonhighered.com/assets/hip/us/hip_us_pearsonhighered/samplechapter/0136016383.pdf