MHS Chemistry
Marble Activity

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!