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): **
This is a resubmission of work that you requested to be resubmitted. I corrected my errors or clock time vs interval time.
** Is flow rate increasing, decreasing, etc.? **
** Is the velocity of the water surface increasing, decreasing, etc.? **
** 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? **
** Explain how we know that a change in velocity implies the action of a force: **
** Does the depth seem to be changing at a regular rate, at a faster and faster rate, or at a slower and slower rate **
** What do you think a graph of depth vs. time would look like? **
** 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? **
** Does this distance change at an increasing, decreasing or steady rate? **
** What do you think a graph of this horizontal distance vs. time would look like? **
** The contents of TIMER program as you submitted them: **
1 1597.703 1597.703
2 1598.516 .8125
3 1599.672 1.15625
4 1601.297 1.625
5 1602.547 1.25
6 1604.266 1.71875
7 1605.75 1.484375
8 1607.141 1.390625
9 1608.766 1.625
10 1610.578 1.8125
11 1612.031 1.453125
12 1613.734 1.703125
13 1615.5 1.765625
14 1617.375 1.875
15 1619.156 1.78125
16 1621.281 2.125
17 1623.047 1.765625
18 1625.156 2.109375
19 1627.063 1.90625
20 1629.5 2.4375
21 1631.891 2.390625
22 1633.656 1.765625
23 1636.719 3.0625
24 1639.359 2.640625
** The vertical positions of the large marks as you reported them, relative to the center of the outflow hole **
0.3
1.4
2.2
3.1
3.9
4.7
5.5
6.3
7.0
7.7
8.5
9.3
10.1
10.8
11.5
12.3
12.8
13.8
14.5
15.2
15.9
16.6
17.4
** Your table for depth (in cm) vs clock time (in seconds) **
0, 17.4
0.81, 16.6
1.96, 15.9
3.59, 15.2
4.84, 14.5
6.56, 13.8
8.04, 13.0
9.43, 12.3
11.06, 12.8
12.87, 11.5
14.32, 10.8
16.02, 10.1
17.79, 9.3
19.67, 8.5
21.45, 7.7
23.58, 7.0
25.35, 6.3
27.46, 5.5
29.37, 4.7
31.81, 3.9
34.21, 3.1
35.98, 2.2
39.04, 1.4
41.68, 0.3
** Is the depth changing at a regular rate, at a faster and faster rate, or at a slower and slower rate? **
Seems to me, except for some anomalies based on my reaction time, that is most certainly supports my original thoughts that the depth is changing at a slower and slower rate.
** Your description of your depth vs. t graph: **
This graph decreases at a decreasing rate. It starts on the vertical axis at 17.4 and 0 seconds and as the line moves to the right the time elapsed is longer for each marked graduation drop.
Do you have a link from another course you offer that more thoroughly describes the Describing Graphs terminology?
The basic terminology is described under the q_a_Init Probs exercise on Describing Graphs. That exercise should be posted on your Access Page.
The graph starts where you say and decreases at a decreasing rate.
** Your explanation and list of average average velocities: **
.8125 = 0.98 cm/sec
1.15625 = 0.61 cm/sec
1.625 = 0.43 cm/sec
1.25 = 0.56 cm/sec
1.71875 = 0.41 cm/sec
1.484375 = 0.54 cm/sec
1.390625 = 0.50 cm/sec
1.625 = 0.43 cm/sec
1.8125 = 0.44 cm/sec
1.453125 = 0.48 cm/sec
1.703125 = 0.41 cm/sec
1.765625 = 0.45 cm/sec
1.875 = 0.43 cm/sec
1.78125 = 0.44 cm/sec
2.125 = 0.32 cm/sec
1.765625 = 0.39 cm/sec
2.109375 = 0.33 cm/sec
1.90625 = 0.42 cm/sec
2.4375 = 0.33 cm/sec
2.390625 = 0.33 cm/sec
1.765625 = 0.45 cm/sec
3.0625 = 0.26 cm/sec
2.640625 = 0.30 cm/sec
2.640625 = 0.30 cm/sec is not a valid statement. 2.640625 is not equal to 0.30 cm/sec. Your intent is clear--the average velocity over the 2.64 second time interval is 0.30 cm / sec. But the equality symbol isn't appropriate.
You could use -> (a dash and a 'greater than' sign), which would indicate implication (e.g., 'this follows from this'). An explanation of meaning at the beginning of the table would also help avoid ambiguity.
In the table below the indicated time interval (which is in seconds) implies the average rate of change of depth with respect to clock time (which is in cm/sec).
.8125 sec -> 0.98 cm/sec
1.15625 sec -> 0.61 cm/sec
1.625 sec -> 0.43 cm/sec
1.25 sec -> 0.56 cm/sec
1.71875 sec -> 0.41 cm/sec
1.484375 sec -> 0.54 cm/sec
1.390625 sec -> 0.50 cm/sec
1.625 sec -> 0.43 cm/sec
1.8125 sec -> 0.44 cm/sec
1.453125 sec -> 0.48 cm/sec
1.703125 sec -> 0.41 cm/sec
1.765625 sec -> 0.45 cm/sec
1.875 sec -> 0.43 cm/sec
1.78125 sec -> 0.44 cm/sec
2.125 sec -> 0.32 cm/sec
1.765625 sec -> 0.39 cm/sec
2.109375 sec -> 0.33 cm/sec
1.90625 sec -> 0.42 cm/sec
2.4375 sec -> 0.33 cm/sec
2.390625 sec -> 0.33 cm/sec
1.765625 sec -> 0.45 cm/sec
3.0625 sec -> 0.26 cm/sec
2.640625 sec -> 0.30 cm/sec
I found avg vel by dividing distance by time elapsed. I. E. 0.8cm / 0.81 would equal .98 cm/sec.
** The midpoints of your time intervals and how you obtained them: **
0.40
1.39
2.21
4.22
5.70
7.30
8.74
10.25
11.97
13.60
15.17
16.91
18.73
20.56
22.52
24.47
26.41
28.42
30.59
31.81
35.41
37.51
40.36
I found these by dividing the time interval in half and adding to the preceding clock time.
That works. You could also have added the two clock times and divided by 2.
This confused me. You are asking for mid-points of the time intervals and according to my original submission's critique you wanted them reported in clock times. Maybe they are clock times by definition. With the word clock time never appearing in the question for this box I am not totally sure how I was to know what to put in here.
I checked the wording and agree that it should be changed. I have clarified with wording for future students.
** Your table of average velocity of water surface vs. clock time: **
0.40, 0.98
1.39, 0.61
2.21, 0.43
4.22, 0.56
5.70, 0.41
7.30, 0.54
8.74, 0.50
10.25, 0.43
11.97, 0.44
13.60, 0.48
15.17, 0.41
16.91, 0.45
18.73, 0.43
20.56, 0.44
22.52, 0.32
24.47, 0.39
26.41, 0.33
28.42, 0.42
30.59, 0.33
31.81, 0.33
35.41, 0.45
37.51, 0.26
40.36, 0.30
** Your description of your graph of average velocity vs clock time: **
Increasing at an increasing rate.
The overall tendency seems to be decreasing average velocities.
** Your explanation of how acceleration values were obtained: **
0.4 cm/sec
0.93
1.88
1.11
0.20
1.37
1.38
1.88
1.86
1.5
1.77
1.95
2.16
2.02
3.31
2.25
3.19
2.26
3.67
3.61
1.95
5.88
4.40
Avg accell = delta v / delta t
On your last interval I see `dt of about 2.85 s and `dv of about +.04 cm/s, yielding `dv / `dt = +.015 cm/s^2, approximately.
The units of `dv / `dt are cm/s^2, not cm/s.
** Your acceleration vs clock time table: **
0.40, 0.4cm/sec
1.39, 0.93
2.21, 1.88
4.22, 1.11
5.70, 0.20
7.30, 1.37
8.74, 1.38
10.25, 1.88
11.97, 1.86
13.60, 1.50
15.17, 1.77
16.91, 1.95
18.73, 2.16
20.56, 2.02
22.52, 3.31
24.47, 2.25
26.41, 3.19
28.42, 2.26
30.59, 3.67
31.81, 3.61
35.41, 1.95
37.51, 5.88
40.36, 4.40
This time it said midpoint clock time and was easier to see the error in my original ways. That doesn't mean I didn't make new errors though.
** According to the evidence here, is acceleration increasing, decreasing, staying the same or is in not possible to tell? **
My result would lead between decreasing to inconclusive. There are, based on my human fallibility, some times that do not seem to correlate with a linear progression of readings. I believe that the acceleration is decreasing.
PS: What I though was ok from the first submission was cut and pasted. I hope the rest is satisfactory.
Everything looks good until your calculation of accelerations, which don't appear to follow from your v vs. midpt t table. See my notes and see if you can give me a revision, including a more detailed explanation of how you calculated the accelerations. You would do `dv / `dt, but your numbers don't seem to come from `dv / `dt.