Phy 232
Your 'flow experiment' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** Your initial message (if any): **
** Is flow rate increasing, decreasing, etc.? **
I would expect the rate of flow to decrease as water flows from the cylinder.
** Is the velocity of the water surface increasing, decreasing, etc.? **
I would expect the velocity of the water surface to decrease as water flows from the cylinder.
** How would the velocity of the water surface, the velocity of the exiting water, the diameter of the cylinder and the diameter of the hole be interrelated? **
By calculating the force of the volume of water in the cylinder that is being exerted, and then find the quotient of water force and the diameter of the hole to determine the pressure that is being exerted as the water flows from the cylinder. A similar ratio can be observed between the velocity of the water surface and the exiting water through the hole. This is done by comparing the ratio of the area of the surface water as seen from above with a circular shape, and comparing that to the area of the hole. This ratio would determine the ratio of velocity between the velocity of the water surface and the exiting water.
** Explain how we know that a change in velocity implies the action of a force: **
The changing velocity implies that the force of the water being exerted upon the entire volume is being focused into a smaller area at the hole in the cylinder. This means that the force applied to the larger area of the water surface is now being applied directly to the smaller area, which creates a greater pressure and velocity.
** Does the depth seem to be changing at a regular rate, at a faster and faster rate, or at a slower and slower rate **
The depth would appear to be changing a a slower and slower rate, because as the depth decreases so does the amount of water above the hole; therefore, the decreased volume exerts a smaller force and less pressure or velocity. This will in turn cause the water level to lower slower, and this process is repeating in cycle exponentially.
** What do you think a graph of depth vs. time would look like? **
I think that the graph would be concave upward starting from a point at t = 0 and depth = initial water level, and that the graph would become a flat line and the point were depth of the water matches that of the hole.
** Does the horizontal distance (the distance to the right, ignoring the up and down distance) traveled by the stream increase or decrease as time goes on? **
It decreases due to the decreased velocity
** Does this distance change at an increasing, decreasing or steady rate? **
This distance decreases at a decreasing rate due to the same logic as how the graph would have a decreasing rate of depth change.
** What do you think a graph of this horizontal distance vs. time would look like? **
At the beginning it would have a fairly high velocity that would quickly drop during the first second or so, and then the curve would show a concave upward trend as the rate of decrease would decrease.
** The contents of TIMER program as you submitted them: **
0.000
2.250
2.352
2.586
2.633
2.930
3.328
3.594
3.805
4.891
6.289
10.922
** The vertical positions of the large marks as you reported them, relative to the center of the outflow hole **
.5
1.6
3.2
4.8
6.3
7.9
9.4
10.9
12.4
13.85
15.3
16.75
** Your table for depth (in cm) vs clock time (in seconds) **
0.000, 16.75
2.250, 15.3
4.602, 13.85
7.188, 12.4
9.820, 10.9
12.750, 9.4
16.078, 7.9
19.672, 6.3
23.477, 4.8
28.367, 3.2
34.656, 1.6
45.578, 0.5
** Is the depth changing at a regular rate, at a faster and faster rate, or at a slower and slower rate? **
A slower and slower rate
** Your description of your depth vs. t graph: **
The graph has a slope that is negative with a decrease rate of change, which creates a concave upward curve. It begins at the point 0, 16.75 and ends with point 45.578, 0.5.
** Your explanation and list of average average velocities: **
I obtained my average values by taking the difference in depths for each time interval and divided by the value of time interval. This gave me the values of:
0.644
0.617
0.561
0.570
0.512
0.451
0.445
0.394
0.327
0.254
0.101
** The midpoints of your time intervals and how you obtained them: **
16.025
14.575
13.125
11.650
10.150
8.650
7.100
5.550
4.000
2.400
1.050
I obtained by finding the sum of two clock times for each interval and dividing by 2.
** Your table of average velocity of water surface vs. clock time: **
16.025, 0.644
14.575, 0.617
13.125, 0.561
11.650, 0.570
10.150, 0.512
8.650, 0.451
7.100, 0.445
5.550, 0.394
4.000, 0.327
2.400, 0.254
1.050, 0.101
** Your description of your graph of average velocity vs clock time: **
The graph has a negative slope with a best fit line that appears to be linear with equation y = -0.01x + 0.66
** Your explanation of how acceleration values were obtained: **
0.012
0.024
-0.003
0.022
0.021
0.002
0.014
0.018
0.015
0.024
0.010
I took the difference between the average velocities of each interval and divided by the time interval.
** Your acceleration vs clock time table: **
1.125, 0.012
3.426, 0.024
5.895, -0.003
8.504, 0.022
11.285, 0.021
14.414, 0.002
17.875, 0.014
21.574, 0.018
25.922, 0.015
31.512, 0.024
40.117, 0.010
** According to the evidence here, is acceleration increasing, decreasing, staying the same or is in not possible to tell? **
The results show that the acceleration seems to be fairly constant, because the variance from a average of the acceleration values is consistently above and below that average; therefore, despite fluctuating values due to experiment error the results show that it is reasonable to conclude a constant acceleration of the water's surface.
** **
1 hour
Excellent work, as expected.