Phy 121
Your 'initial timing 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.
** template formInitial Timing Experiment
You may enter any message or comment you wish in the box below:
________________ **
** ________
In this experiment you will use the TIMER program, a hardcover book, a cylinder or some other object that will roll along the book in a relatively straight line, and a ruler or the equivalent (if you don't have one, note the RULERS link on the Assignments page).
- The book's cover should be straight and unbent.
- The object should roll fairly smoothly.
Place the book on a flat level tabletop. You will prop one end of the book up a little bit, so that when it is released the object will roll without your assistance, gradually speeding up, from the propped-up end to the lower end. However don't prop the end up too much. It should take at least two seconds for the ball to roll down the length of the book when it is released from rest.
- Using the TIMER program determine how long it takes the ball to roll from one end of the ramp to the other, when released from rest. Time the object's motion at least five times.
- Determine how far the object actually travels as it rolls from one end to the other.
- Determine how much higher one end of the book was than the other, and how far it is from one end to the other.
Then reverse the direction of the book on the tabletop, rotating the book and its prop 180 degrees so that the ball will roll in exactly the opposite direction. Repeat your measurements.
In the box below describe your setup, being as specific as possible about the book used (title, ISBN) and the object being used (e.g., a solid glass marble, a small can of tomato paste (full or empty?), a ball-point pen), and what you used to prop the object up (be as specific as possible). Also describe how well the object rolled--did it roll smoothly, did it speed up and slow down, did it roll in a straight line or did its direction change somewhat?
Note: Don't trust this form. Compose your answer in Notepad or a word processor, saving it every few minutes, then copy and paste it into the box. Power could surge, your computer could malfunction, in any of a number of ways the work you put into this form could be lost. Compose it elsewhere and keep a copy.
________________ **
I used the book Big Book of Animals authored by Nathan Hamilton and Deborah Chancellor, published by Igloo Books Ltd, ISBN: 9781848173187 on which the cylinder rolled. The book measures 31.6 cm in length (the direction the cylinder rolled), 24.4 cm in width, and 1.3 cm in height. I propped the book up with another book Now You’re Cookin’ Tuscany, published by Rebo Publishers, ISBN 13: 9789036614832 which measures 24.4 cm in length, 21.6 cm in width, and 1.2 cm in height. I placed this book under the first so as to lift the top edge of the first book 2 cm above the table. I used a 213 gram full can of SpaghettiOs as a cylinder to roll down the book. The height of the can measures 7.5 cm with a diameter of 6.7 cm. I then timed 4 rolls of the can down the book, starting the timer when I released the can and stopping it when the can reached the end of the book. I used the same procedure after I turned the books 180 degrees. The can rolled very smoothly down the book. During the first rolls, the way the book was initially oriented, the can did roll at a slight angle down the book. Once the book was turned 180 degrees, it appeared the can rolled in a straight line. The can did not speed up and slow down. It only appeared to roll faster the further it traveled.
** ________
In the box below report your data. State exactly what was measured, how it was measured, how accurately you believe it was measured and of course what the measurements were. Try to organize your report so the reader can easily scan your data and see any patterns that might occur.
________________ **
I used the TIMER program and began timing rolls as I released the can at the top edge of the book. I stopped the timer the instant the can reached the bottom of the book. This was done as accurately as possible with room for human error in reaction times and restrictions of the TIMER program. The first 4 rolls from the top edge to the bottom edge of the book were as follows: 2.648438s, 2.664063s, 2.761719s, 2.542969s. After turning the books 180 degrees and rolling the can from the top edge to the bottom edge I received the following results: 2.335938s, 2.226563s, 2.316406s, 2.195313s.
** ________
Using your data determine how fast the object was moving, on the average, as it rolled down the incline. Estimate how accurately you believe you were able to determine the object's average speed, and give the best reasons you can for your estimate of the accuracy.
________________ **
To determine how fast the can was moving I have divided the times it took for the can to travel by the distance it traveled. For the first orientation of the book and the can rolling all the way down the book it was traveling at average speeds of 11.93 cm/s, 11.86 cm/s, 11.44 cm/s, 12.43 cm/s (31.6 cm / 2.648438 s; 31.6 cm / 2.664063 s; 31.6 cm / 2.761719 s; and 31.6 cm / 2.542969 s respectively). Once the book was turned 180 degrees it traveled at speeds of 13.53 cm/s, 14.19 cm/s, 13.64 cm/s, 14.39 cm/s (31.6 cm / 2.335938 s; 31.6 cm / 2.226563 s; 31.6 cm / 2.316406 s; 31.6 cm / 2.195313 s). Of course there is room for human error in timing this experiment because the can should roll at the same speed down the book because all aspects of the experiment remained the same among all rolls. Therefore, I have taken an average of the first 4 rolls and the second set of 4 rolls. The can was traveling an average of 11.92 cm/s and 13.94 cm/s, respectively. Again, the experiment was the same between both sets of rolls except that the book was inclined in the opposite direction on the table. Although the table appeared to be level, the difference in times indicates that the table may have a slight incline so that when the book was turned 180 degrees, the can rolled slightly faster. Also, as mentioned previously, the can did roll at a slight angle on the original orientation of the book which could skew these results because of extending the length of travel.
** ________
Devise and concuct an experiment to determine whether or not the object is speeding up as it rolls down the incline. If you have set the experiment up as indicated, it should seem pretty obvious that the object is in fact speeding up. But figure out a way to use actual measurements to support your belief.
Explain how you designed and conducted your experiment, give your data and explain how your data support your conclusions.
________________ **
I placed the top edge of a mouse pad approximately halfway down the book, 15.6 cm from the top where the can was released and timed 4 rolls from the top of the book to the edge of the mouse pad (while the book was turned the 180 degrees from the prior step of this experiment). I timed the can taking 1.199219 s, 1.400625 s, 1.425781 s, and 1.355469 s to travel this distance. Using this data we can determine the can was traveling at average speeds of 13.01 cm/s, 11.14 cm/s, 10.94 cm/s, and 11.51 cm/s (15.6 cm / 1.199219 s; 15.6 cm / 1.400625 s; 15.6 cm / 1.425781 s; 15.6 cm / 1.355469, respectively). Again, to compensate for human error in reaction time and timing I have averaged these average to speeds to gather that on average the can was traveling an average speed of 11.65 cm/s during the rolls down the first half of the book. As I determined earlier over the course of the entire book the can traveled at an average speed of 13.94 cm/s which means it must have sped up over the course of the distance and been traveling faster later on. Also, we could say that it took an average of 2.268555 s to travel 31.6 cm based on the data presented above ((2.335938 s + 2.226563 s + 2.316406 s + 2.195313 s) / 4). Based on the present data, it took an average of 1.3452735 s ((1.199219 s + 1.400625 s +1.425781 s + 1.355469 s) / 4) to travel the first 15.6 cm. Therefore, it took only 0.9232815 s (2.268555 s – 1.3452735 s) to travel the lower 16 cm. It took less time to travel a further distance so the book must have been traveling at a greater speed. We could also average that the book was traveling at an average speed of 17.329493 cm /s (16 cm / 0.9232815 s) along the lower half of the book. This is faster than the 13.94 cm/s average speed we found it to be rolling over the course of the upper 15.6 cm. In order for the average speed to be higher, the can must have been speeding up.
** ________
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?
________________ **
An hour and a half including reporting this data
** ________
You may add optional comments and/or questions in the box below.
________________ **
&#Good responses. Let me know if you have questions. &#