This activity is a model of a method to find the diameter of objects that can't
easily be measured directly. You should put a piece of masking tape one
meter wide on the floor, and another short piece a meter away. Place 3
to 10 marbles evenly spaced on the long piece of tape (mark their positions
with a pen first), then pitch a marble in their direction from the one-meter-away
mark. If you hit a marble, replace it on it's mark for the next pitch.
Repeat at least 50 times each, counting the number of hits and misses.
The sphere diameter can be calculated by the formula:
| calculated sphere diameter = | (field width) X (hits) |
| 2 (targets) X (throws) |
The sphere diameter will be in whatever units the field width
is given in.
| Data & Results | ||
| A | width of field (cm) | |
| B | number of target spheres | |
| C | total number of hits | |
| D | total number of throws | |
| E | calculated sphere diameter | |
| F | volume of water (mL) | |
| G | volume of water + spheres (mL) | |
| H | volume of spheres (mL) | |
| I | number of spheres in cylinder | |
| J | average volume of sphere (mL) | |
| K | measured diameter of sphere (cm) | |
| L | % difference of measured from calculated | |
For the calculated sphere diameter (E) in the data table, use the formula given
above the data table.
For the measured sphere diameter (K), use the average volume of a sphere (J),
and the formula for the volume of a sphere.
| V= | 4pr 3 |
| 3 |
|
You'll have to solve for r (radius). Don't worry that volume is in mL; one milliliter is the same as one cubic centimeter. Also, don't forget to change the radius into a diameter.
Finally, calculate the % "error" of your calculated sphere diameter (E) from the measured sphere diameter (K). Assume that the measured sphere diameter is the true value.
What to Pass In
Make sure you pass in the data table completed (it can be this sheet).
Attach a sheet showing all your calculations. Don't forget a title
section!