initial timing experiment

PHY 201

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 form

Initial 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).

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.

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 our classes Physics book by Giancoli (isbn:0-13-060620-0) for the platform, rested one end on a small cd case (5mm thick), and rolled a full, unopened 12oz. coca-cola can. The can rolled very smoothly and seemed to speed up a little towards the bottom of the ramp.

** ________

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.

________________ **

Run Distance Traveled Time

1 275mm 2.156s

2 275mm 2.344s

3 275mm 2.313s

4 275mm 2.764s

5 275mm 2.915s

6 275mm 2.321s

Runs 1-3 were in the starting position described in your instructs.

Runs 4-6 were measured when the book was rotate 180 degrees.

** ________

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.

________________ **

Run Calculation Speed

1 275mm/2.156s 127.55 mm/s

2 275mm/2.344s 117.32 mm/s

3 275mm/2.313s 118.89 mm/s

4 275mm/2.764s 99.49 mm/s

5 275mm/2.915s 94.34 mm/s

6 275mm/2.321s 118.48 mm/s

I believe the readings and calculations were very accurately timed, but since the object was round and a little bigger, it was hard to measure from the exact tangent point that it was started. I rolled the object until it fell off the side so the ended measuring point was precise.

** ________

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 used a longer object for the ramp (580mm long) made from aluminum. The can was used again and the object proped under the ramp platform was a Papermate White Pearl eraser (10mm thick). I started the timer from the point that I let it start to roll, and stopped the time halfway down to record that time, and stopped the timer at the end to get the total time, and time difference between halfway and the whole way. The object was definitely speeding up near the bottom of the ramp since the time recorded was significantley shorter, leading to the calculation to determine the speed difference.

** ________

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: 

________________ **

45 minutes

** ________


You may add optional comments and/or questions in the box below.

________________ **

&#Very good work. Let me know if you have questions. &#