FOLLOW THE (physicists call it Coefficient of Restitution)

1. Find a dictionary and find out what in the world RESTITUTION means: _____________________

_______________________________________________________________________________.

2. Now, what does COEFFICIENT mean in math? _______________________________________

______________________________________________________________________________.

PURPOSE: (also called why are we doing this?)

To get a good grade. . Um, I mean, "To graphically investigate the relationship between the height a ball is dropped and the height to which it bounces. This will be called the coefficient of restitution."

3. So, what is a Coefficient of Restitution as it applies to energy? ___________________________

________________________________________________________________________________.

PROCEDURE: (also called how we did it)

1. Get a meter stick and one of each type of ball.

2. Hold the ball at the 100 cm mark and let it drop to the floor and from a level, straight-on view (ask about "parallax") observe to what height it bounces. Repeat this three more times so you can get an average value. Record your data in the data table. (Don't forget to label each column with the unit of measure!)

3. Repeat this procedure from the 80, 40, 20, and 0 (yes, 0. You'll see why. And, yes, I know I skipped 60 cm) centimeter marks.

1. Do steps 2 and 3 for each of the remaining balls. Also, label each column with which ball it represents so you know which is which.

   Drop ht. BALL_____________ BALL_____________ BALL_____________ BALL _____________

   100

   1^st ___ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   80

   1^st ___ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   40

   1^st ___ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   20

   1^st ___ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   1^st ____ 2^nd ____ 3^rd____ Average= ________

   0

   Average= ________

   Average= ________

   Average= ________

   Average= ________

   7. Now, get a piece of graph paper and graph the bounce height vs. drop height or do it on the graphical analysis program (we use Microsoft Excel). (Remember which goes on the y-axis?)

   8. Use those algebra one skills or the Excel program to find the slope of each line (you are to do a "Trend-line" also called a "Best-fit line" NOT a "Smoothed Line" if you use Excel). (The slope IS the coefficient of restitution, by the way.)

   9. What does the slope tell you about the ball? _________________________________________

   10. DON'T MAKE THIS STEP HARD! Write an equation for the relationship of drop height to bounce height for each ball (Excel can give you this): Use "D" for the drop variable and "B" for the bounce variable.

   BALL ____________ EQUATION _____________

   BALL ____________ EQUATION _____________

   BALL ____________ EQUATION _____________

   BALL ____________ EQUATION _____________

   11. Now, look at your slopes and the type of ball. The slope, when written as a decimal, shows you what percentage of energy the ball retains after each bounce. What are the percentages for each ball in descending order (tell which ball is which also)?

   _______________, _______________, _______________, _______________.

   12. Look at your graph and list the ball with the steepest line first, and so on.

   _______________, _______________, _______________, _______________.

   13. Look at your answers for #11 and #12. See any similarities? What is it? ________________

   14. If you used MS Excel for your graph, the equation of each ball's trend-line most likely did NOT go

   through the origin (or you could say the y-intercept was not zero). If you drew a best-fit line it probably did not go through the origin. This indicates that if you drop the ball from zero height, the ball does NOT have zero bounce. Explain why the equation indicates this:

   ___________________________________________________________________________

   ___________________________________________________________________________.

   15. Why do you place dropping the ball from zero in your data chart? _______________________

   ___________________________________________________________________________.

   (Check these items before handing in: did you label the units for each column of your chart, on your graph - did you label your axes (units and what each axis represents), did you label each line with the name of the ball it represents, did you use a STRAIGHT LINE and NOT a connect-the-dot approach, did you make your graph background white and not gray, did you write your equations, is your fly closed?)