Experiment 1-4

How Much Space is Wasted?

Background Information

Sometimes we want to measure something that is difficult to do directly.  It is often possible to use an indirect method whereby we do easier measurements and then calculate what must be the desired measurement.  (Some view such an ability to find the easiest method to reach an answer is a sign of intelligence.)  This experiment will use an indirect method called displacement

Consider some sand:  The grains must not fit tightly but rather have gaps between the grains, probably usually filled with air.  How much space is between the sand grains?  For industries who need to pack material into the minimum of volume, this might be considered wasted space.  For creatures that live in soil, this is vital space that provides room for essential water and oxygen.  For plants, soil that packs too tightly with little volume for water could doom survival in dry times.  For a company that produces concrete, knowing the amount of space between gravel allows the maximization of profits by minimizing sand and cement.

Procedure

For a selected sample of sand, gravel, or other granular material, determine the percentage of volume between the granules.  Recall from Experiment 1-3 that there can be difficulties transferring materials from one location to another.  Minimize losses due to transfers.

1. Measure the apparent volume of the dry granules,
2. then transfer the dry granules to a storage location for step 4.
3. Measure about an equal volume of water.
4. Add the granules to the water and note the water's meniscus.  Caution: Discard granules in an appropriate manner.  For example, sand should not be flushed down a drain.
Sum the volumes of the dry granules (granules with air in the gaps: step 1) and the volume of the water (step 3).  The shortage between the combined volume (water with granules: step 4) and this sum is the air volume.

Divide the volume of air by the granular volume (step 1), then multiple by 100% to determine the percentage of volume between the granules.

Record your results in your science journal and write a formal report to earn credit.