Upcoming SlideShare
×

# Lab report waves

2,472 views
2,338 views

Published on

0 Likes
Statistics
Notes
• Full Name
Comment goes here.

Are you sure you want to Yes No
• Be the first to comment

• Be the first to like this

Views
Total views
2,472
On SlideShare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
22
0
Likes
0
Embeds 0
No embeds

No notes for slide

### Lab report waves

1. 1. Jeremy Logrono Physics 5th period Mr. Eales Lab Report: Waves Introduction: A tsunami is a good example of a shallow-water wave. They are called shallow-water waves because when these waves travel in the ocean, the relationship of the water depth and wavelengths are small. Unlike other waves that are typically blown by the wind in an ocean surface, tsunami waves can travel as fast as 800 km per hour and the wavelengths are massive. As the waves approach the shore and hits the rising sea level, it reduces the velocity of the waves. When the velocity of the wave lessens, the wavelengths become shortened and thus the wave heights increases which can cause destruction to a nearby shore. (http://britannica.com/EBchecked/topic/607892/tsunami) Figure 1: a diagram of how tsunami waves generate This phenomenon has a relationship between the velocities of a shallow-water wave and the depth of the water which the equation is: [1] Since the velocity of the tsunami is related to the water depth, as the depth of the water decreases, the velocity of the tsunami decreases. (http://www.tulane.edu/tsunami.htm) In comparison of a tsunami wave, the aim of this investigation is to find the relationship between the speed and depth for a single pulse of wave travelling across a shallow basin of water.
2. 2. Design: Research Question: What is the relationship between the speed and depth for a single pulse travelling across a shallow basin of water? Variables: The dependent variable was the depth of the water in the basin and the independent variable was the speed of a single pulse of a wave across the basin. There were also several controlled variables that were kept constant in this investigation. By only using one basin with the same distance, the distance of the wave can be remained constant. The liquid used in this investigation was constantly the tap water. The method of timing, which is a handheld stopwatch was also constantly been used during the investigation. The temperature was controlled by only staying inside the room to keep the room temperature constant. For each trial of “flicking” (hitting the basin of water with a finger) was been constantly performed by only one person. This investigation began when 480 ml of water was dispensed in the basin, measured by an accurate liquid measurement tool; the graduated cylinder. There were 3 time trials in 6 different volumes. Since the volume starts with 480 ml of water, it was then increased in doubled to start the next volume. After dispensing each of the specific water volumes in the basin, the side of the basin was then flicked with a finger. Once the finger has hit the basin, the person who held the stopwatch has started the time recording. What was being recorded in this investigation was how fast a single pulse of wave can travel across the basin. The person who has recorded the time needed to watch the wave closely and press the stop button when the wave hit the end of the basin. These procedures have been done 6 times with 1 constant person to flick the basin and 1 constant person to record the times of the waves through out the investigation.
3. 3. Data Collection and Processing: Sample Calculations: 1.) Uncertainty of average time of 1 single pulse (960 ml): = (Trial 2 – Trial 1) = (1.43 – 1.25)/2 = 0.09 = ± 0.1/s 2.) Uncertainty of the depth (480 ml): Length of the basin = 37.2 cm (± 0.1) Width of the basin = 29.6 cm (± 0.1) (Highest possible depth – lowest possible depth) (481/37.1*29.5) = 0.4394 - 0.4323 = (479/37.3*29.7) 2 = ± .004 Table 1 Volume(ml) (± 1) Trial 1 (± 0.1/s) Trial 2 (± 0.1/s) Trial 3 (± 0.1/s) Average (± 0.1/s) 480 1.28 1.27 1.22 1.3 960 1.25 1.43 1.32 1.3 1440 1.53 1.56 1.54 1.5 1920 1.91 1.85 1.81 1.9 2400 1.97 2.01 2.03 2.0 2880 2.03 2.03 2.12 2.1 Table 1: These are the recorded times in seconds of the pulse waves in different depths Table 2 Volume(ml)(± 1) Depth (± .004) Distance (±0.1) Time(S(±0.1) Speed (cm/s)(±2) 480 0.436 37.2 1.3 30 960 0.872 37.2 1.3 28 1440 1.308 37.2 1.5 24 1920 1.744 37.2 1.9 20 2400 2.180 37.2 2.0 19 2880 2.616 37.2 2.1 18 Table 2: These are the processed data from excel; the uncertainties and the average time
4. 4. Depth vs. Speed Figure 2: The original data of depth of the basin vs. the speed of the single pulse wave with a negative slope or linear fit. 1/Depth vs. Speed Figure 3: The changed depth of the original data as; 1/depth vs. speed to show a positive slope or linear fit
5. 5. Conclusion and Evaluation: According to figure 2 which is the original data, it shows the negative relationship between the speed and depth of a single pulse of a wave. This illustrates that as the depth of the basin increases, the speed of the wave decreases. Also, according to figure 3, when the depth is inverted (1/depth), the relationship of the speed and depth become positive. By doing 1 divided by the depth, the depth increases and therefore the inverse value decreases. In the graph, the actual data points showed that there were deviations or uncertainties from the calculated linear fit. The size of the uncertainty reflects the accuracy of this investigation. By looking at the correlation of figure 3 graph, the correlation is 90% and therefore the confidence level of this investigation is high. The results of this investigation confirm the relationship of depth of speed of a single pulse wave. Also, the results can only be applied to a small basin of depth and cannot be compared to a tsunami wave. A tsunami wave consists of the gravity factor [1] - which is not being measured in this investigation and therefore the results cannot be applied to the wave of a tsunami. There were some errors and weaknesses in this experiment that needs improvements. One of the weaknesses of this investigation is how the wave was generated within the basin. In this investigation, the action of “flicking” the side of the basin was the use of a finger and this generates the single pulse wave. The person who was doing the “flicking” may have not control his own strength and therefore the production of the single pulse wave were not constant and may have affected the recorded times. This weakness can be improved if there was a device that can control and unleash a constant force through the basin. Also, the timing and the observations of the single pulse waves can be inaccurate. The waves were sometimes faintly seen and the person who was observing the wave may have experienced inaccuracy of timing whether the wave hits the end of the basin in time. This weakness can be improved if there was an advanced timing device present in this investigation.