How Water Effects Friction When Walking Downhill by Ethan Riggs

The past few days here on Colgate's campus have been very dreary and full of rain. Since I and many others live down the hill we have to deal with the slippery slope that comes about due to the rain. On one of these fateful thunderous nights, the rain was coming down particularly hard as I approached the hill leading past the library to Willow Path. As I walked down the hill I could feel just how slippery the asphalt was when water was on it. I remember testing it out by swinging my leg and having it slide right across the ground with little resistance.

What is happening here? It seems that when it rains the water makes the asphalt more slippery because of a lower friction force between my shoe and the ground. If we think back to the equation Ffr = 𝜇k FN we notice that the coefficient of kinetic friction is directly related to the force of friction. We learned in class that the coefficient of friction is a number that is specific to the two materials in contact. When comparing the force of friction between my shoe and the asphalt it can be concluded that Ffr is greater when there is no rain and lower when there is rain. Since the normal friction does not change, we can then make the assumption that when rain is present on the asphalt the force of friction between my shoe and the asphalt is lower than without the rain. This supports what we talked about in class about the coefficient of friction being specific to the two materials interacting and can change when one of the surfaces is altered.

I have had fun thinking about how physics affects my daily life and will continue to see the world differently while also being safe when walking down the many campus hills.