Friction: Definition
Friction, in simplest terms is a resistance to the relative motion of two objects. It is an inherent force that resists the motion of an object that is in contact with other object. If you try to move a heavy book kept on a table, you will have to apply some force to move the book. Why do you need some force to move the book? This is because the frictional force between the contact area of book and table, is resisting the motion of the book. Have you ever tried ice skating? You must be wondering that there is no friction when you're ice skating and that is why, it's easier to slide so easily on the ice. It is not that there is zero friction between the ice and skates. Zero friction is an ideal concept, one that we use in solving theoretical problems. In the practical world, some friction always exists between two objects coming in contact with each other. Hence, in the case of ice skating, there is friction, but it is very less, making it easier for skaters to perform ice skating. If practically friction becomes zero, it would be impossible for skaters to stop, or for you to sit on a chair, or run on the road. You will keep running indefinitely, in absence of friction!
Is Friction a Force?
Did you notice that we referred to friction as a force while defining it? You must understand that friction is a force that is resistive in nature. It obstructs the motion of another object by applying some force. Are you not wondering from where are frictional forces generated? Let us understand friction, from a molecular level. Ordinary friction that we observe in daily life can be thought of to be a result of roughness in surface. This was what scientists believed for a long time as the main cause of friction. However, today studies have suggested molecular adhesion and plowing effect to be the major causes of friction.
Molecular adhesion is defined as the force that exists between two surfaces coming in contact by the virtue of molecular or electromagnetic attractions between the molecules. To overcome resistance, it becomes essential to break the molecular attraction bond or the adhesive bond. Plowing effect is the frictional force that occurs due to the deformation in size of the object near the point of contact. For example, if a hard object slides on a soft platform, it is the deformation in shape of the surface of soft object that generates friction.
What Friction is Measured In
Friction being a force, the SI unit of measurement of friction is Newton. The value of frictional force that acts between objects in relative motion depends on two major quantities, that is, coefficient of friction µ and net normal reaction N. The frictional force equation is given by, F = μN,
where, μ = coefficient friction, and N = net normal reaction
Understanding the coefficient of friction or μ is very important to calculate understand this concept completely. Coefficient of friction is a scalar quantity that represents the resistance that a surface exerts on substances moving over it. Mathematically, it is the ratio between the frictional force between the surfaces and the force that is applied on the bodies. The coefficient of static friction is a term that is referred for static objects while the term coefficient of kinetic friction is a measure of friction for objects in motion.
Friction, in simplest terms is a resistance to the relative motion of two objects. It is an inherent force that resists the motion of an object that is in contact with other object. If you try to move a heavy book kept on a table, you will have to apply some force to move the book. Why do you need some force to move the book? This is because the frictional force between the contact area of book and table, is resisting the motion of the book. Have you ever tried ice skating? You must be wondering that there is no friction when you're ice skating and that is why, it's easier to slide so easily on the ice. It is not that there is zero friction between the ice and skates. Zero friction is an ideal concept, one that we use in solving theoretical problems. In the practical world, some friction always exists between two objects coming in contact with each other. Hence, in the case of ice skating, there is friction, but it is very less, making it easier for skaters to perform ice skating. If practically friction becomes zero, it would be impossible for skaters to stop, or for you to sit on a chair, or run on the road. You will keep running indefinitely, in absence of friction!
Is Friction a Force?
Did you notice that we referred to friction as a force while defining it? You must understand that friction is a force that is resistive in nature. It obstructs the motion of another object by applying some force. Are you not wondering from where are frictional forces generated? Let us understand friction, from a molecular level. Ordinary friction that we observe in daily life can be thought of to be a result of roughness in surface. This was what scientists believed for a long time as the main cause of friction. However, today studies have suggested molecular adhesion and plowing effect to be the major causes of friction.
Molecular adhesion is defined as the force that exists between two surfaces coming in contact by the virtue of molecular or electromagnetic attractions between the molecules. To overcome resistance, it becomes essential to break the molecular attraction bond or the adhesive bond. Plowing effect is the frictional force that occurs due to the deformation in size of the object near the point of contact. For example, if a hard object slides on a soft platform, it is the deformation in shape of the surface of soft object that generates friction.
What Friction is Measured In
Friction being a force, the SI unit of measurement of friction is Newton. The value of frictional force that acts between objects in relative motion depends on two major quantities, that is, coefficient of friction µ and net normal reaction N. The frictional force equation is given by, F = μN,
where, μ = coefficient friction, and N = net normal reaction
Understanding the coefficient of friction or μ is very important to calculate understand this concept completely. Coefficient of friction is a scalar quantity that represents the resistance that a surface exerts on substances moving over it. Mathematically, it is the ratio between the frictional force between the surfaces and the force that is applied on the bodies. The coefficient of static friction is a term that is referred for static objects while the term coefficient of kinetic friction is a measure of friction for objects in motion.
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