initial timing experiment

Phy 231

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 the back side of my Phychology book. ISBN-13: 978-0-536-24725-4. The book is 28 cm long. I propped it up using two coasters that were each .5 cm thick. So the book was propped up 1 cm. The last .25 cm of the book were on top of the coasters. I used and unsharpened pencil to roll down the book. The pencil rolled down in a straight line increasing in speed the whole time.

** ________

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.

________________ **

Ramp going down from left to right.

1 2.433594

2 2.058594

3 2.335938

4 2.234375

Ramp reversed, going down from right to left.

1 2.070313

2 2.320313

3 2.082031

4 2.109375

I measured these numbers using the TIMER program. I would press the click to time event button when the pencil started rolling at the top pf the ramp and again when it got to the bottom. I believe these measurements to be very accurate.

** ________

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.

________________ **

On average the pencil rolled down the ramp at a speed of 12.7 cm per second. I believe this number to be very accurate because I took the average of the time for each direction, found the speed for each direction by dividing that average by 28, and then I added those two numbers and divided by 2 to get an overall average of 12.7 cm/sec.

** ________

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 did the experiment just as before except I added in another time interval in the middle of the ramp, 14cm from the beginning. This way I record how long it takes to the pencil to reach the middle of the ramp and how long it takes it to reach the end from the middle. If the data supported my hypothesis that the pencil speeds up going down the ramp then the second interval should be smaller than the first.

The data I recorded is:

Start to Mid Mid to End

1 1.554688 .6914063

2 1.278125 .7539063

3 1.25625 .7539063

4 1.523438 .765625

The data in all four trials supported my hypothesis. It did not take as long for the pencil to roll down the second half of the ramp as it did the first with both being equal lengths. This means the pencil 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: 

________________ **

1 hour

** ________


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

________________ **

&#This looks good. Let me know if you have any questions. &#