Friction and Temperature

Every day, millions of rubber tires are rolling around all over the world. These tires belong to a vast variety of equipment that includes wheelbarrows, cars, trucks, airplanes, and even monster trucks. Such rubber-wheeled equipment may be found operating in environments ranging from -50°C to 45°C, and this variance in temperature can greatly affect the performance of the tires.

In this experiment, a lab was created to test how temperature affects the amount of friction rubber exerts on a surface. Frictional force is defined by the following equation:

Ff = Cf · FN

In other words, the Force of Friction (Ff) that rubber applies on a surface is equal to the Coefficient of Friction (Cf) multiplied by the Normal Force (FN), where normal force is the product of the object's mass and the acceleration of gravity. The Normal Force will always be constant as long as the mass and gravity's acceleration don't change, so the variable in this equation happens to be the Coefficient of Friction.

By altering the Coefficient of Friction, the Force of Friction will be altered. How does one alter the Coefficient of Friction? In this experiment, a difference in temperatures between trials will influence the Coefficient of Friction. The greater the Coefficient of Friction, the greater the Force of Friction will be, and thus more force may be applied to the rubber before it begins to move, and vice-versa. This fact is what the experiment is based on. How does the temperature of the rubber affect the amount of friction it exerts on a surface? The rubber with the higher temperature will have a higher force of friction because its shape will conform to the surface it is in contact with due to its chemical composition.

After all of the data was collected, all three trials from each 'temperature setting' (hot, cold, room temp.) of rubber temperatures for each specimen were averaged. Then, that average was averaged with the results of the same 'temperature setting' from the other specimen. These overall averages were then converted into force by the following equation:

Force = Mass · Acceleration

In this case, the acceleration used in the calculations was the acceleration of gravity: -9.81 m/s2*. This was multiplied by the average weight that was required to cause the specimens to move for an averaged temperature. For the room temperature trials, the average force required to move both specimen A and B was .2742 Newtons at ...