If two surfaces with different coefficients of friction are sliding against each other, the surface with the lower coefficient of friction will generally break first. This is because the coefficient of friction determines the amount of resistance between the two surfaces and affects the forces at play during sliding.
There are two types of friction to consider: static friction and kinetic friction. Static friction is the force that opposes the initiation of motion between two surfaces, while kinetic friction is the force that opposes the relative motion of two surfaces in contact.
When two surfaces are initially at rest, static friction prevents them from sliding against each other until a certain force, known as the maximum static friction force, is applied. The maximum static friction force is directly proportional to the coefficient of static friction between the surfaces. Once the applied force exceeds this threshold, the static friction is overcome, and the surfaces start moving, transitioning into kinetic friction.
The coefficient of kinetic friction is generally lower than the coefficient of static friction for a given pair of surfaces. It represents the resistance to motion once the surfaces are already in motion. The kinetic friction force is proportional to the coefficient of kinetic friction.
In the context of your question, if two surfaces have different coefficients of friction, the one with the lower coefficient will have less resistance to motion and will, therefore, be more likely to break first. The lower coefficient of friction implies that the surface experiences less frictional force, requiring a smaller force to overcome it and initiate motion. Consequently, it is more susceptible to sliding or breaking.
However, it's important to note that the breaking or failure of surfaces is influenced by various factors, such as the materials involved, their strength, and other mechanical properties. The coefficients of friction alone do not provide a complete picture of the structural integrity or failure mechanism of the surfaces.