The cement had the next highest coefficient Of friction Which is expected because it has similar properties to pavement which highways are made with. The coefficient is less then the one with sandpaper but there is still enough friction to allow a car to drive safely on it. The coefficient of friction of the wood is a lot lower then the cement and sandpaper surfaces. This shows that there is not enough friction between rubber and some surfaces which would cause the tire o slip and as a result the car will go off the road.
Since the coefficient of friction of the wood is so much smaller then that of the sandpaper and cement imagine how small the coefficient of friction between the rubber and ice would be! It wood be smaller then that of the wood because ice is more slippery then wood, CONCLUSION: Since the coefficient of friction of the wood is so much smaller then the sandpaper and cement it shows why it is harder to drive on some surfaces then others. This lab also shows why sand is put on icy roads to increase the amount of friction between the two surfaces.