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.? **
It appears as though the rate of flow decreases, beacuse the stream of soda exits with less force as time passes. This could be related to Bernoulli's equation.
** Is the velocity of the water surface increasing, decreasing, etc.? **
I imagine velocity would decrease, because it appears that the water is exiting the hole in the cylinder more slowly as time passes.
** 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? **
Velocity of water surface would increase when the diameter of the hole increased or velocity of exiting water increased. The velocity of water surface would decrease if the diameter of the cylinder was increased.
** Explain how we know that a change in velocity implies the action of a force: **
Acceleration = velocity / time.
average acceleration is change in velocity / change in clock time; velocity / time doesn't have an important meaning. For example if you are driving at 30 m/s at a time 20 minutes after starting out, your acceleration is not 30 m/s / (20 minutes). However if your velocity changes from 30 m/s to 32 m/s during a 10-second interval, your acceleration would be 2 m/s / (10 s) = .2 m/s^2.
Force = acceleration * mass.
So an change in velocity implies a change in acceleration, which implies a change in force (gravity), based on the above equations.
Good reasoning.
** 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 dpeth appears to change at a slower and slower rate because the stream of soda covers gradually less distance.
** What do you think a graph of depth vs. time would look like? **
Depth decreases with as time increases.
** 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? **
The horizontal distance increases as time goes on
** Does this distance change at an increasing, decreasing or steady rate? **
This seems to change at an increasing rate.
** What do you think a graph of this horizontal distance vs. time would look like? **
Horizontal distance decreases as time increases.
** The contents of TIMER program as you submitted them: **
1 2380.75 2380.75
2 2382.656 1.90625
3 2384.938 2.28125
4 2387.547 2.609375
5 2390.438 2.890625
6 2393.016 2.578125
7 2396.141 3.125
8 2399.844 3.703125
9 2403.391 3.546875
10 2407.859 4.46875
11 2412.391 4.53125
12 2418.109 5.71875
13 2420.141 2.03125
** The vertical positions of the large marks as you reported them, relative to the center of the outflow hole **
0
.5
2.1
3.6
5.1
6.6
8.1
9.5
10.9
12.4
** Your table for depth (in cm) vs clock time (in seconds) **
0, 12.4
2.89, 10.9
5.47, 9.5
8.60, 8.1
12.3, 6.6
15.8, 5.1
20.5, 3.6
25.0, 2.1
30.8, .5
32.8, 0
** 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 rate. You can see this because the time it takes for 20 mL of water to leave the outlet decreases as the water level decreases. This supports the above data.
** Your description of your depth vs. t graph: **
The graph of depth vs. clock time is decreasing at a decreasing rate from left to right.
** Your explanation and list of average average velocities: **
The average velocity for the water as it decreased by 1.5 cm was found by dividing the distance traveled by the time taken to travel. Ex: 1.5 cm / 2.89 sec = .519 cm/s velocity. The following velocities are in units of cm/s.
0.519
0.543
0.448
0.405
0.423
0.336
0.331
0.227
0.246
** The midpoints of your time intervals and how you obtained them: **
The midpoints for the time intervals were taken from the information given in the timer program. The timer program gives the amount of time between each click. So I divided this by 2 to come up with the midpoint for each time interval, which are as follows:
1.45
2.74
4.3
6.15
7.9
10.3
12.5
15.4
16.4
Your last time interval runs from 30.8 s to 32.8 s. The midpoint of this interval is 31.8 s, not 16.4 s. The clock time 16.4 s is not even in the interval.
This table and subsequent results based on it need to be revised. Just submit a copy of this document and indicate your revisions by &&&&.
** Your table of average velocity of water surface vs. clock time: **
0, 0
1.45, .519
2.74, .543
4.3, .448
6.15, .405
7.9, .423
10.3, .336
12.5, .331
15.4, .227
16.4, .246
** Your description of your graph of average velocity vs clock time: **
The overall graph is decreasing, though at points it has small increases.
** Your explanation of how acceleration values were obtained: **
The average acceleration for each time interval was found by dividing velocity/midpoint time. The units are cm/s/s.
0.358
0.198
0.104
0.066
0.054
0.033
0.026
0.015
0.015
Even if your midpoint clcok times were correct (and they can be easily corrected), your results would not indicate accelerations. See my preceding note.
The changes in clock times would be the intervals between midpoint clock times.
** Your acceleration vs clock time table: **
1.45, 0.358
2.74, 0.198
4.3, 0.104
6.15, 0.066
7.9, 0.054
10.3, 0.033
12.5, 0.026
15.4, 0.015
16.4, 0.015
** According to the evidence here, is acceleration increasing, decreasing, staying the same or is in not possible to tell? **
The data shows that the acceleration of water in decreasing. I think this is correct.
You have very good data and everything is correct to the point where you calculate midpoint clock times. Please see my notes and take a few minutes to revise; if it takes you much longer than that send me some questions about anything that's giving you trouble.