# Homework Help: An investigation on the factors affecting skiing

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1. Feb 16, 2015

### maturk

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >

Hello everybody! I am posting this in hopes of further guidance and help on a high school essay assignment.

I am required to make an investigation with an experiment(s) that explores a certain physical phenomena (preferably classical physics). The maximum word count for this assignment is 4,000 words which means I have a lot of room for mathematics, an experiment(s), and thorough analysis. Lately I have been thinking of topics such as the physics of skipping stones (very difficult to experiment in a high school laboratory), tipping vs slipping (too simple in my opinion for this large essay), and even physics of slinkys; however, I have had immense trouble thinking of experiments for these topics that are advanced and technical enough to be analysed in depth. For this essay, it was suggested to have theoretical and experimental portions in it just like many other real physics papers that have both theoretical accepts and some experimentation on these accepts.

Now I am thinking about writing this essay about the factors that affect the maximum velocity of downhill skiing.
The factors that I already have in mind are:
• The methods of decreasing friction between the skis and snow with wax and things like that.
• I could also analyse how a person should stand on the skis (center of gravity) that would allow the fastest speed. (This is probably fully theoretical and probably doesn't need an experiment).
• The shape of the skis.
• The angle of the slope that the person (or experimental object) skiis down. Not sure if this is any good though, because wouldn't higher angles just make the person go faster (at least in my head)?
• The quality of snow i.e. densly packed or lightly packed, ice vs snow, and things like that.
So, those are the things I have thought of so far. The only thing is that... I don't know what sort of experiments I could do to test these factors or the sort of theoretical physics that I should do (like math and all). After all this is a long physics assignment that will require a lot of mathematics, analysis, and physics. Note, I am only a high school student with access to an ordinary school laboratory, so doing really fancy stuff with cool equipment and all doesn't seem very feasible. I really like this topic right now and I am trying to pursue it.

Anyways, do you guys have any experiments in mind that I could do to test these factors?
Any suggestions for further analysis and/or factors to consider?
Any theoretical ideas I should try to do and research?
Any opinions about the "goodness" or worth of my chosen topic?

Last edited by a moderator: Feb 16, 2015
2. Feb 16, 2015

### dean barry

There are three forces involved.
For:
Driving force of gravity.
(dependent on skier mass and incline angle)
Against:
Opposing force of air drag.
(proportional to the velocity squared)
Opposing force of sliding friction.
(deemed to be constant, regardless of speed)

Acceleration at any given speed (below terminal) is: net force / mass
Top speed (terminal speed) is when the for and against forces balance.

3. Feb 16, 2015

### dean barry

You might also consider altitude, which changes the force of air drag, due to the variable density of the air with different altitudes above sea level.

4. Feb 16, 2015

### driesvdb

Hey,

I'm an alpine ski racer, fastest snow is spring snow, when it melts the day before and gets frozen over night, in the morning the slope is very very hard and icy but not as cold as ice, because very cold snow is really slow. You need to wax a very hard hydrocarbon wax as a base and then a very high fluor wax. The Center of mass should be in front of your ankles, just look up downhill position on google. Or speed skiing. Fast ski's are not width, but if you make them too small you won't be stable and. not be able to reach your max speed when you have to stand up out of your downhill position to look for balance.

5. Feb 16, 2015