Human Power eJournal
Contents | About | Contact

Editorial 07, issue 01

Resistance on snow and ice

by Theo Schmidt
illustration by Charles Snyder
December 21, 2004

HPeJ has now been going for about half a year with an article or something on the 21st of each month and with several articles in the queue for next year. However please continue to send articles and information for publication! And Season's Greetings to you all!

Santa on sledThis being the cold, snowy season in the northern hemisphere, articles on ice-skating, cross-country skiing or studded tires would seem appropriate, but: some of you readers must write them first! Or at least send data or pictures. I would like to assemble data on the resistance of steel blades on ice, skis on snow, and sleds on both. Measuring these is not too difficult: you need a spring scale and a rope for pulling a skater/skier/sled, and a bathroom scale for weighing people or loads so that the non-dimensional coefficient similar to the coefficient of rolling resistance can be determined. This is simply the  pulling force  divided by the force acting at a right angle to this. This so-called normal force is approximately the weight at small slopes, or more precisely the mass in kg times the local gravitational acceleration (about 9.8 m/s^2) times the cosine of the slope (gives Newtons).

spring scaleFirst, find a dead flat surface like a frozen lake or a skating rink and experiment on different qualities of ice and snow, also describing this quality (e.g. smooth white ice, perfect clear ice, bumpy ice, hard snow). If you aren't sure about the slope, do measurements in several directions. Do this at rather slow speeds and record the speed approximately. Although sliding friction is usually assumed to be speed-independent, in practice you will notice some increase with pulling speed.

animated slopeOr, if there is a slope and you can measure it, determine the angle where the skier/sled/etc. just begins to move; then the spring scale isn't required. 

Send your data by email via the contact link below.

Contents | About | Contact

Human Power eJournal