Conditions to produce sliding friction
There are several conditions that people must consider. First of all, the surface needs to be rough enough to allow the object to slide slowly and we can measure and do some experiments. Although there has never been a frictionless surface on earth, scientists have yet to find an easy place to study this research. Second, kinetic friction only occurs when two objects contact each other. During the same time, the energy moving towards two objects is converted into thermal energy. A typical example is that people rub their hands to keep warm in the winter. Also, two objects slide on the surface of the other object. The direction of the kinetic friction is against the direction of the sliding motion and the point of action is on the object affected by it.
The advantages and disadvantages of sliding friction
Because friction works to prevent changes in motion, whether it is helpful or harmful depending on your situation. If people want to move something more easily, it is detrimental because they should use more force to move that object. One way to reduce that force is to add a ball or wheel under that object, because at this moment, the rolling friction is less than the kinetic friction. There are many common examples to explain this statement, such as cars that we drive that have four wheels, large suitcases that we use to travel that have two or four wheels, even huge trucks that have multiple rows of wheels to help reduce force. Another way to reduce friction is to change the surface materials. For example, it is easier to move an object on ice than on wood because ice is softer than wood. Also, to make machines and engines last longer, workers put oil on them, so they won’t erode or damage very soon.
However, it has the advantage of helping us maintain the original movement. Sometimes we need this kind of force to get a stationary motion, and we even have to increase the sliding force. When it rains, the road becomes smoother, so smart people make wheels rougher like tire tread to prevent cars from slipping. When people go hiking, they wear special walking shoes that use more rubber and add shoe prints to keep people standing on rocks.
Experiment to discover the main factors affecting sliding friction
The scientists take three equal slopes and three wooden blocks that have the same shape and mass on a horizontal table, but use different surface materials such as glass, wood, and sand and place them evenly on the slope. They use a spring dynamometer to measure sliding friction to move the object at a constant speed. The higher the sliding friction, the rougher the surface. Consequently, they can summarize that the coefficient influences. If the scientists hold all the conditions except the mass of the object and the material on the surface. This time they use objects that have different mass (various forces between slope and block) and change the surface of various materials to the same. The result is that the greater the mass, the greater the sliding friction. In summary, two main factors that influence kinetic friction are the coefficient and the force between two objects.