The accompanying photograph is of a rock located on the campus of Old Dominion University (in Norfolk, Virginia). Every week or so during the semester, different student organizations paint the rock in expressions of support for various communities and movements both locally and nationally.

If the rock is painted about every week throughout two 15-week semesters, how many 1-gallon (~4-L) cans of paint would be required? I placed my hat on the rock for the purposes of scale.

Estimate the mass of the rock and the mass of one coat of (dry) paint covering the surface.

Look for the answers online at tpt.aapt.org under “Browse,” at the very end of the current issue.

Dr. John A. Adam has been professor of mathematics at Old Dominion University since 1984. His PhD from the University of London was in theoretical astrophysics (an exceedingly long time ago). As an undergraduate, he was exposed...

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