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 this rate to decrease as the amount of water in the cylinder decreases. The amount of weight of liquid on top of the liquid exiting is decreases, so the reduced force would reduce the velocity of the liquid.
Is the velocity of the water surface increasing, decreasing, etc.?
SInce the velocity of the water surface is related to the velocity of the exiting water, the descent of the buoy would decrease as the surface velocity decreases as a result of the exit velocity decreasing.
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?
The velocity of the water surface would be related to the velocity of the exiting water since it is reliant on the rate of the water's exit. The diameter of the cylinder would be important since the wider the cylinder, the slower the liquid's exit and therefore descent. A narrower cylinder would mean a faster relative descent of the liquid since there is not as much in a cross sectional area of the cylinder. The diameter of the hole is the most influential piece of data as this determines the velocity at which the liquid can leave the cylinder, and therefore lower the level of the water surface.
Explain how we know that a change in velocity implies the action of a force:
The change in velocity is the acceleration of the water. This, when multiplied by the mass of the water, will define the force of the water as it descends.
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 changes at a slower and slower rate as the water exits.
What do you think a graph of depth vs. time would look like?
I think it would be a concave up curve downwards asymptotically approaching zero.
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?
decrease. the water does not shoot out as far.
Does this distance change at an increasing, decreasing or steady rate?
it changes at a decreasing rate, meaning the water is slowing more and more slowly.
What do you think a graph of this horizontal distance vs. time would look like?
i think it would also be a concave upwards curve that is decreasing at a decreasing rate.
The contents of TIMER program as you submitted them:
1 77.91406 77.91406
2 78.85156 .9375
3 79.9375 1.085938
4 80.94531 1.007813
5 82.03906 1.09375
6 83.21094 1.171875
7 84.49219 1.28125
8 85.97656 1.484375
9 87.78125 1.804688
10 89.82031 2.039063
11 92.59375 2.773438
12 97.66406 5.070313
13 98.96094 1.296875
The vertical positions of the large marks as you reported them, relative to the center of the outflow hole
.7cm
2.7cm
4.7cm
6.6cm
8.6cm
10.5cm
12.4cm
14.2cm
16.1cm
17.9cm
19.8cm
21.6cm
Your table for depth (in cm) vs clock time (in seconds)
0.9375, 21.6cm
1.0859, 19.8cm
1.0078, 17.9cm
1.0938, 16.1cm
1.1719, 14.2cm
1.2813, 12.4cm
1.4844, 10.5cm
1.8047, 8.6cm
2.0391, 6.6cm
2.7734, 4.7cm
5.0703, 2.7cm
1.2969, .7cm
The clock keeps running, so clock tims is a strictly increasing quantity. It looks like clock time runs about 20 seconds for this experiment.
I believe your table indicates depth vs. time interval, not depth vs. clock time.
Is the depth changing at a regular rate, at a faster and faster rate, or at a slower and slower rate?
The depth is changing at a slower and slower rate as the water level decreases.
Your description of your depth vs. t graph:
Overall, there is a concave up curve decreasing at a decreasing rate. however, there is one erroneous point occuring at 0.7cm, 1.2969s. the reason is point does not follow the trend and jumps backwards from the curve is it seems to have been a much shorter time, but the distance the water traveled in that time is also smaller. As a result, this influential point makes the graph look odd, but if the measurements were calibrated based on distance traveled, it would not be an outlier.
It sounds like you're describing a graph of depth vs. time interval, depth vs. `dt instead of depth vs. t
Your explanation and list of average average velocities:
The average velocities were found by dividing the distance traveled by the amount of time needed to travel that distance. All measurements are in cm/s:
v=s/t
23.04
18.23372318
17.76146061
14.71932712
12.11707484
9.677671115
7.073565077
4.765334959
3.236722083
1.694670801
0.532512869
0.539748631
The midpoints of your time intervals and how you obtained them:
the midpoint of the time interval is simply the point exactly halfway through the time elapsed between measurements (in seconds), so the time interval was divided by two:
0.46875
0.54295
0.5039
0.5469
0.58595
0.64065
0.7422
0.90235
1.01955
1.3867
2.53515
0.64845
The midpoint of a time interval is the instant halfway between the two clock times. This is not the same thing as half the time interval (see previous notes).
Your table of average velocity of water surface vs. clock time:
0.46875, 23.04
0.54295, 18.23372318
0.5039, 17.76146061
0.5469, 14.71932712
0.58595, 12.11707484
0.64065, 9.677671115
0.7422, 7.073565077
0.90235, 4.765334959
1.01955, 3.236722083
1.3867, 1.694670801
2.53515, 0.532512869
0.64845, 0.539748631
Your midpoint clock times are not correct, per previous notes.
Your description of your graph of average velocity vs clock time:
there is a concave up curve decreasing at a decreasing rate. Again, the outlier showed again because its time interval is so much shorter than the previous measurement. It did not have the same distance to travel, so did not use the same amount of time.
Your explanation of how acceleration values were obtained:
As acceleration is the rate of change of velocity (cm/s), we divide the velocity by the time (in this case, the median time):
Measurements are in cm/s^2:
49.152
33.58269303
35.24798692
26.91411065
20.67936656
15.10601907
9.530537694
5.281027272
3.174657529
1.222088989
0.210051819
0.832367386
Your acceleration vs clock time table:
49.152, 0.46875
33.58269303, 0.54295
35.24798692, 0.5039
26.91411065, 0.5469
20.67936656, 0.58595
15.10601907, 0.64065
9.530537694, 0.7422
5.281027272, 0.90235
3.174657529, 1.01955
1.222088989, 1.3867
0.210051819, 2.53515
0.832367386, 0.64845
According to the evidence here, is acceleration increasing, decreasing, staying the same or is in not possible to tell?
This shows that over time, the acceleration of the water is generally decreasing. I believe the acceleration of the water is decreasing as the water exits the graduated cylinder.
You have good data, but you are not interpreting the phrase 'clock time' correctly, and this causes some problems with your analysis. See my notes and send me a copy of this document with your revisions; indicate your revisions by *&*&.