Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Skipping Rocks 
Name: Matthew H.
Status: student
Age: 10
Location: N/A
Country: N/A
Date: 4/22/2003
Question:
How do rocks skip across water?

Replies:
As the rock hits the water, it must be tilted up somewhat or at least the front edge must be bevelled. Otherwise, it can dig its way into the water, ending its skipping career.

Then when the rock strikes the water, it pushes the water down. By Newton's Third Law (For every force there is an equal and opposite reaction force) the water exerts an upward and slightly backward force on the rock. The upward force pushes the rock back up into the air and the backward force slows the rock, hopefully slightly.

Usually the rock is given a strong spin so that, like a gyroscope, it tends to keep its orientation. I used to be reasonably skilled at skipping stones (due to much practice). My record, I believe, is 10 skips...

Best, Dick Plano, Professor of Physics emeritus, Rutgers University


Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory