#$&*
Phy 201
Your 'energy conversion 1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** Energy Conversion 1_labelMessages **
12:55 pm EST 7/7/14. I only did the 1 rubber band because this part to a very long time.
** **
Note that the data program is in a continual state of revision and should be downloaded with every lab.
Most students report completion times between 2 and 3 hours, with some as short as 1 hour and some as long as 5 hours.
For part of this experiment you will use the calibrated rubber band you used in the preceding experiment 'Force vs. Displacement 1', as well as the results you noted
for that experiment.
For this experiment you will need to use at least one rubber band in such a way as to make it useless for subsequent experiments. DO NOT USE ONE OF YOUR CALIBRATED
RUBBER BANDS. Also note that you will use four of the thin rubber bands in a subsequent experiment, so DO NOT USE THOSE RUBBER BANDS HERE.
If your kit has extra rubber bands in addition to these, you may use one of them.
You are going to use the rubber band to bind three of your dominoes into a block. If you don't have extra rubber bands, you could use some of the thread that came with
your kit, but rubber bands are easier to use.
The idea of binding the dominoes is very simple. Just set one domino on a tabletop so that it lies on one of its long edges. Then set another right next to it, so the
faces of the two dominoes (the flat sides with the dots) are touching. Set a third domino in the same way, so you have a 'block' of three dominoes.
Bind the three dominoes together into a 'block' using a rubber band or several loops of thread, wrapping horizontally around the middle of the 'block', oriented in
such a way that the block remains in contact with the table. The figure below shows three dominoes bound in this manner, resting on a tabletop.
Now place a piece of paper flat on the table, and place the block on the paper, with the block at one end of the paper.
Give the block a little push, hard enough that it slides about half the length of the paper.
Give it a harder push, so that it slides about the length of the paper, but not quite.
Give it a push that's hard enough to send it past the other end of the paper.
You might need to slide the block a little further than the length of one sheet, so add a second sheet of paper:
Place another piece of paper end-to-end with your first sheet.
Tuck the edge of one sheet slightly under the other, so that if the block slides across the first sheet it can slide smoothly onto the second.
You are going to use a calibrated rubber band to accelerate the blocks and make them slide across the table.
Tie two pieces of thread through to the rubber bands holding the blocks, at the two ends of the block, so that if you wanted you could pull the block along with the
threads. One thread should be a couple feet long--long enough that if the block is at one edge of one paper, the other end of the thread extends beyond the edge of the
other paper. The other thread needs to be only long enough that you can grasp it and pull the block back against a small resistance.
At the free end of the longer thread, tie a hook made from a paper clip.
Use the rubber band you used in the preceding experiment (the 'first rubber band' from your kit, the one for which you obtained the average force * distance results).
Hook that rubber band to the hook at the free end of the longer thread.
Make another hook, and put it through the other end of the rubber band loop, so that when you pull on this hook the rubber band stretches slightly, the string becomes
taut and the block slides across the tabletop.
You will need something to which to attach the last hook:
Now place on the tabletop some object, heavy enough and of appropriate shape, so that the last hook can in one way or another be fixed to that object, and the object
is heavy enough to remain in place if the rubber band is stretched within its limits. That is, the object should be able so remain stationary if a few Newtons of
force is applied. Any rigid object weighing, or being weighted by, about 5-10 pounds ought to be sufficient.
Your goal is to end up with a moderately massive object, to which the last hook is tied or attached, with the rubber band extending from the hook to another hook, a
thread from that hook to the block (with a shorter thread trailing from the other end of the block)
With a slight tension in the system the block should be a few centimeters from the 'far' edge of the paper which is furthest from the massive object.
If the block is pulled back a little ways (not so much that the rubber band exceeds its maximum tolerated length) the rubber band will stretch but the last hook will
remain in place, and if the block is then released the rubber band will snap back and pull the block across the tabletop until the rubber band goes slack and the block
then coasts to rest.
The figure below shows the block resting on the paper, with the thread running from a hook to the rubber band at the far end, which is in turn hooked to the base of a
flatscreen monitor.
At the far end the rubber band is ready to be stretched between two hooks. A measuring device is shown next to the rubber band; to get accurate measurements of rubber
band length it is recommended that a piece of paper be placed beneath the rubber band, and two points carefully marked on the paper to indicate the positions of the
ends. The separation of the points can later be measured. Alternatively the two points can be marked in advance at the desired separation and the system stretched
accordingly.
Consult your previous results and determine the rubber band length required to support the weight of two dominoes. Pulling by the shorter piece of thread (the 'tail'
of thread), pull the block back until the rubber band reaches this length, and on the paper mark the position of the center of the block (there might well be a mark at
the center of the domino; if not, make one, being sure it is within 1 millimeter of the center, and mark the paper according to this mark). Release the thread and see
whether or not the block moves. If it does, mark the position where it comes to rest as follows:
Make a mark on the paper where the center mark comes to rest by drawing a short line segment, perhaps 3 mm long, starting from the center mark and running
perpendicular to the length of the block.
Make another mark about twice the length of the first, along the edge of the block centered at the center mark.
This will result in a mark that looks something like the following, with the longer line indicating the direction of the block and the two lines coming together at the
center mark: __|__. In the first figure below the lowest two marks represent the positions of the center of the dominoes at initial point and at the pullback point.
The mark next to the domino is the horizontal part of a mark that looks something like |- ; the vertical part of that mark is obscured by the blocks, and the mark it
also tilted a bit to coincide with the slightly rotated orientation of the block. In the second figure most of the |- mark can be seen.
You will make a similar mark for the final position for each trial of the experiment, and from these marks you will later be able to tell where the center mark ended
up for each trial, and the approximate orientation of the block at the end of each trial.
Based on this first mark, how far, in cm, did the block travel after being released, and through approximately how many degrees did it rotate before coming to rest?
If the block didn't move, your answers to both of these questions will be 0.
Answer in comma-delimited format in the first line below. Give a brief explanation of the meaning of your numbers starting in the second line.
Your answer (start in the next line):
2.85 cm from pullback or 1.60 cm from inital, 3-5 degrees
The marks were measured from the center of the dominoes at initial unstretched length and when the rubberband was pulled to 7.05 cm (legth of tention for 2 dominoes).
#$&* _ 2 rb tension how far and thru what angle
Tape the paper to the tabletop, or otherwise ensure that it doesn't move during subsequent trials.
Repeat the previous instruction until you have completed five trials with the rubber band at same length as before.
Report your results in the same format as before, in 5 lines. Starting in the sixth line give a brief description of the meaning of your numbers and how they were
obtained:
Your answer (start in the next line):
2.5cm pullback, 1.55cm initial, 10 degrees
1.7cm from pullback, 0.95cm from initial, 25 degrees
2.4cm from pullback, 1.1 cm from initial, 2-3 degrees
2.0 cm from pullback, 0.95cm from initial, 2-3 degrees
2.4cm from pullback, 1.2cm from initial, 5 degrees
#$&* _ trials on paper
Now, without making any marks, pull back a bit further and release.
Make sure the length of the rubber band doesn't exceed its original length by more than 30%, with within that restriction what rubber band length will cause the block
to slide a total of 5 cm, then 10 cm, then 15 cm.
You don't need to measure anything with great precision, and you don't need to record more than one trial for each sliding distance, but for the trials you record:
The block should rotate as little as possible, through no more than about 30 degrees of total rotation, and
it should slide the whole distance, without skipping or bouncing along.
You can adjust the position of the rubber band that holds the block together, the angle at which you hold the 'tail', etc., to eliminate skipping and bouncing, and
keep rotation to a minimum.
Indicate in the first comma-delimited line the rubber band lengths that resulted in 5 cm, 10 cm and 15 cm slides. If some of these distances were not possible within
the 30% restriction on the stretch of the rubber band, indicate this in the second line. Starting in the third line give a brief description of the meaning of these
numbers.
Your answer (start in the next line):
7.1cm, 7.8 cm, 8.0cm
#$&* _ rb lengths for 5, 10, 15 cm slides
Now record 5 trials, but this time with the rubber band tension equal to that observed (in the preceding experiment) when supporting 4 dominoes. Mark and report only
trials in which the block rotated through less than 30 degrees, and in which the block remained in sliding contact with the paper throughout.
Report your distance and rotation in the same format as before, in 5 lines. Briefly describe what your results mean, starting in the sixth line:
Your answer (start in the next line):
4.4cm from pullpack, 2.7cm from initial, 2-3 degrees
4.3cm from pullback, 2.6cm from initial, 2-3 degrees
4.9cm from pullback, 3.0cm from initial, 5 degrees
6.1cm from pullback, 4.3cm from inital, 2-3 degrees
5.3cm from pullback, 3.4cm from inital, 2-3 degrees
#$&* _ 5 trials 4 domino length
Repeat with the rubber band tension equal to that observed when supporting 6 dominoes and report in the same format below, with a brief description starting in the
sixth line:
Your answer (start in the next line):
6.2cm from pullpack, 3.8cm from intial, 2-3 degrees
8.4cm from pullback, 6.2 from initial, 10 degrees
6.0 from pullback, 3.6 from initial, 2-3 degrees
9.1 from pullback, 6.9 from initial, 2-3 degrees
8.5 from pullback, 6.3cm from initial, 2-3 degrees
#$&* _ 5 trials for 6 domino length
Repeat with the rubber band tension equal to that observed when supporting 8 dominoes and report in the same format below, including a brief description starting in
the sixth line:
Your answer (start in the next line):
7.8cm from pullback, 5.2cm from initial, 2-3 degrees
7.8cm from pullback, 5.2cm from initial, 2-3 degrees
7.8cm from pullback, 5.2cm from initial, 2-3 degrees
6.0cm from pullback, 3.7 from initial2-3 degrees
7.7cm from pullback, 5.1 from initial, 2-3 degrees
#$&* _ 5 trials for 8 domino length
Repeat with the rubber band tension equal to that observed when supporting 10 dominoes and report in the same format below, including your brief description as before:
Your answer (start in the next line):
20.0cm from pullback, 17.1cm from initial, 2-3 degrees
24.0cm from pullback, 21.1cm from initial, 2-3 degrees
25.4cm from pullback, 22.5cm from inital, 2-3 degrees
25.5cm from pullback, 22.6cm from initial, 2-3 degrees
26.7cm from pullback, 23.9cm from initia, l2-3 degrees
#$&* _ 5 trials for 10 domino length
In the preceding experiment you calculated the energy associated with each of the stretches used in this experiment.
The question we wish to answer here is how that energy is related to the resulting sliding distance.
For each set of 5 trials, find the mean and standard deviation of the 5 distances. You may use the data analysis program or any other means you might prefer.
In the space below, report in five comma-delimited lines, one for each set of trials, the length of the rubber band, the number of dominoes supported at this length,
the mean and the standard deviation of the sliding distance in cm, and the energy associated with the stretch.
You might choose to report energy here in Joules, in ergs, in Newton * cm or in Newton * mm. Any of these choices is acceptable.
Starting in the sixth line specify the units of your reported energy and a brief description of how your results were obtained. Include your detailed calculations and
specific explanation for the third interval. Be sure to give a good description of how you obtained the energy associated with each stretch:
Your answer (start in the next line):
7.05cm, 2 dominoes, 2.2 cm (mean), 0.3391 std dev, 0.0074Ncm
7.08cm, 4 dominoes, 5cm (mean), 0.7348 std dev, 0.185Ncm
7.52cm, 6 dominoes, 7.64cm (mean), 1.433 std dev, 0.626Ncm
7.55cm, 8 dominoes, 7.42cm (mean), 0.7949 std dev, 0.667Ncm
7.75cm, 10 dominoes, 24.32cm (mean), 2.597 std dev, 0.979Ncm
#$&* _ for each set of trials length, # dom, mean, std of sliding dist, energy _ describe how results obtained esp energy calculations
Sketch a graph of sliding distance vs. energy, as reported in the preceding space .
Fit the best possible straight line to your graph, and give in the first comma-delimited line the slope and vertical intercept of your line.
In the second line specify the units of the slope and the vertical intercept.
Starting in the third line describe how closely your data points cluster about the line, and whether the data points seem to indicate a straight-line relationship or
whether they appear to indicate some sort of curvature.
If curvature is indicated, describe whether the curvature appears to indicate upward concavity (for this increasing graph, increasing at an increasing rate) or
downward concavity (for this increasing graph, increasing at a decreasing rate).
Your answer (start in the next line):
Slope of 0.36 and y int of -3.1
Newtons for the slope and N*cm for y int
The points are somewhat close to the line but not that close with 3 points below and 2 above. The graph has downward concavity.
@&
The graph of sliding distance vs. energy has a rise on the order of 20 cm and a run on the order of 1 N cm.
The slope is on the order of 20 N^-1.
If your slope is in Newtons it might indicate that you reversed the axes of your graph.
*@
#$&* _ sliding dist vs. energy slope, vert intercept of st line, how close to line, describe curvature if any
Now repeat the entire procedure and analysis, but add a second rubber band to the system, in series with the first.
For each trial, stretch until the first rubber band is at the length corresponding to the specified number of dominoes, then measure the second rubber band and record
this length with your results.
When graphing mean sliding distance vs. energy, assume for now that the second rubber band contributes an amount of energy equal to that of the first. You will
therefore use double the energy you did previously.
When you have completed the entire procedure report your results in the space es below, as indicated:
Report in comma-delimited format the length of the first rubber band when supporting the specified number of dominoes, and the length you measured in this experiment
for second band. You will have a pair of lengths corresponding to two dominoes, four dominoes, ..., ten dominoes. Report in 5 lines:
Your answer (start in the next line):
I'll have to end here as he first part took quite a long time.
#$&* _ lengths of 1st and 2d rbs in series each of 5 trials
Report for each set of 5 trials your mean sliding distance and the corresponding standard deviation; you did five sets of 5 trials so you will report five lines of
data, with two numbers in each line:
Your answer (start in the next line):
#$&* _ sliding dist and std dev each tension
Give the information from your graph:
Give in the first comma-delimited line the slope and vertical intercept of your line.
In the second line specify the units of the slope and the vertical intercept.
Starting in the third line describe how closely your data points cluster about the line, and whether the data points seem to indicate a straight-line relationship or
whether they appear to indicate some sort of curvature.
If curvature is indicated, describe whether the curvature appears to indicate upward concavity (for this increasing graph, increasing at an increasing rate) or
downward concavity (for this increasing graph, increasing at a decreasing rate).
Your answer (start in the next line):
#$&* _ slope, vert intercept, describe curvature
In the space below, report in the first line, in comma-delimited format, the sliding distance with 1 rubber band under 2-domino tension, then the sliding distance with
2 rubber bands under the same 2-domino tension.
Then in the subsequent lines report the same information for 4-, 6-, 8- and 10-domino tensions.
You will have five lines with two numbers in each line:
Your answer (start in the next line):
#$&* _ 5 lines comparing 1 rb to 2 rb trials
Your preceding answers constitute a table of 2-rubber-band sliding distances vs. 1-rubber-band sliding distances.
Sketch a graph of this information, fit a straight line and determine its y-intercept, its slope, and other characteristics as specified:
Give in the first comma-delimited line the slope and vertical intercept of your line.
In the second line specify the units of the slope and the vertical intercept.
Starting in the third line describe how closely your data points cluster about the line, and whether the data points seem to indicate a straight-line relationship or
whether they appear to indicate some sort of curvature.
If curvature is indicated, describe whether the curvature appears to indicate upward concavity (for this increasing graph, increasing at an increasing rate) or
downward concavity (for this increasing graph, increasing at a decreasing rate).
Your answer (start in the next line):
#$&* _ graph 2 rb dist vs 1 rb dist _ slope and intercept _ describe any curvature
To what extent do you believe this experiment supports the following hypotheses:
The sliding distance is directly proportional to the amount of energy required to stretch the rubber band. If two rubber bands are used the sliding distance is
determined by the total amount of energy required to stretch them.
Your answer (start in the next line):
#$&* _to what extend is hypothesis of sliding dist prop stretching energy supported _ to what extent for 2 rb
Your instructor is trying to gauge the typical time spent by students on these experiments. Please answer the following question as accurately as you can,
understanding that your answer will be used only for the stated purpose and has no bearing on your grades:
Approximately how long did it take you to complete this experiment?
Your answer (start in the next line):
:
#$&*
*#&!
@&
You stopped short of the end, but you got to the central point of the exercise.
However you appear to have reversed the axes of your graph.
This should be easy and quick to correct.
Please use #### for your insertions.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
*@