On the sports field, teams A and B are engaged in a tug of war competition. Players from both sides are pulling with all their might, the commanders on either side are vigorously waving flags, and the audience is shouting loudly, "Go! Go!" After an intense struggle, team A finally emerges victorious. People congratulate team A and some even give them a thumbs up, saying, "The members of team A are really strong!"

Is the winning side in a tug of war competition simply stronger?

Before answering this question, let's conduct an experiment: take two spring scales, hook them onto each other, and have individuals from teams A and B pull on each scale. Upon careful observation of the readings on the two scales, you'll notice that despite the back-and-forth pulling between the two teams, there's always an equality in the readings on the two spring scales. The winning side doesn't show higher readings than the losing side. Even if person A exerts no force and lets person B pull alone, the readings on both spring scales remain equal.

This suggests that in a tug of war competition, the force exerted by team A on team B and the force exerted by team B on team A are a pair of equal magnitude and opposite direction forces. So, why does one side win? What's the secret to winning?

Imagine if all members of team A were wearing roller skates while team B members wore shoes with rough tire soles. In this scenario, the victory wouldn't belong to team A anymore. Regardless of how much force team A applies, they will be pulled over by team B.

This shows that the outcome of a tug of war isn't solely determined by the forces applied in opposite directions, but is closely related to the frictional force between the participants' feet and the ground.

During a tug of war, the key is to increase the friction between your feet and the ground while preventing yourself from being pulled forward by the opposing team. This requires pushing against the ground and leaning backward. As a person's weight increases, the frictional force with the ground also increases. Therefore, tug of war competitions typically involve participants with greater body weight, and athletes often prefer wearing shoes with rough soles.

Because a tug of war competition doesn't truly measure who's stronger, it's not an official sport. Instead, it remains a recreational athletic activity.

In reality, friction is everywhere and often brings troubles: worn-out shoe soles, aged clothing, damaged bicycles, watches, and more. Statistics show that around half of one's income is spent compensating for various types of wear and tear.

For many years, friction has been both a friend and a foe to humanity, benefiting and consuming human effort, resources, and finances. Especially for industrial products, friction is a major adversary to their quality and lifespan. It's said that the wear and tear costs for a U.S. Navy aircraft flying for an hour surpass its fuel costs. In challenging environments, friction leads to machine malfunctions and part damage, among other issues. With advances in science and technology, as modern mechanical products move toward high speed, heavy load, and high temperature conditions, the problem of friction becomes more prominent, gradually evolving into a significant field of study for humanity – the field of tribology.

In simple terms, tribology is the collective term for the science and technology that studies the interconnected aspects of friction, wear, and lubrication on the surfaces of two objects. As the materials on the contact surfaces of two objects continuously wear away, a series of physical, chemical, and mechanical changes occur.

Tribology aims to analyze the changes on the frictional surfaces of objects, propose corresponding technical measures, reduce or eliminate unnecessary material and energy losses, and design various new types of mechanical and lubrication products. Therefore, tribology is a comprehensive interdisciplinary subject that involves fields such as mathematics, mechanics, physics, chemistry, metallurgy, mechanical engineering, material science, and petroleum engineering.

The scope of study in tribology is vast, including the design of typical friction components such as bearings, gears, turbines, seals, clutches, the selection of friction materials and surface treatment technologies, and the choice of various lubrication materials and techniques. It also encompasses the analysis, monitoring, and prediction of machine wear incidents.

Today, the study of tribology has extended to the movement of human joints and the opening and closing of heart valves, giving rise to branches such as biotribology and psychological tribology. Recently, some have linked the theory of crustal movement to the formation of mountains, oceans, and faults, suggesting a connection between volcanic eruptions, earthquakes, and tribology. This is known as "geotribology."

As a practical technological discipline, tribology holds significant economic value. Approximately one-third of the world's total energy consumption ultimately transforms into some form of frictional loss. By reducing friction, a substantial amount of energy could be conserved.

In recent years, industrialized nations have shown great interest in studying and developing tribology, investigating their own national tribological situations. Their collective conclusion is that if the existing knowledge of tribology were widely applied in industry, it could potentially increase the gross domestic product (GDP) by about 1%[1]. This is a remarkable figure.