Research into friction is essential for advanced nanotechnology. It is essential in everyday life although often we expend a lot of effort to try to minimise it effects and so reduce energy loss and wear and tear on moving parts. Friction is the name given to the force that opposes the motion of one body sliding over another.
It is called friction when the objects are solid, viscosity in liquids but it always opposes the motion of an object. The first mathematical description was made by Charles Augustine de Coloumb in He proposed that friction could be classed as static or dynamic and proposed that the frictional force was frictional force dependent on the materials in contact. At an interface between two objects, the surfaces may appear to be smooth, however on a microscopic scale the surfaces are pitted and jagged.
When another similar surface is in contact with it, the irregularities and peaks interlock. Australian Physicist, Frank Philip Bowden who worked on friction is quoted as saying: "Putting two solids together is rather like turning Switzerland upside down and standing it on Austria—the area of contact would be small.
The friction force depends on two factors: a The materials that are in contact. The two materials and the nature of their surfaces. Rougher surfaces have higher coefficient of frictions but to slide apart.
This makes sense in terms of a model in which friction is described as arising from chemical bonds between the atoms of the two surfaces at their points of contact: very flat surfaces allow more atoms to come in contact b The force pushing the two surfaces together. I am talking about contact area, not surface area. Suppose you put a rubber ball on a glass plate. As you push down on the rubber ball, it will deform such that more of the ball will come in "contact" with the glass.
Here is a diagram of this. Greater contact area means greater frictional force. If the contact area is proportional to the normal force, then this looks just like Amontons' Law with the frictional force proportional to the normal force. Of course this model "breaks" when the contact area can no longer increase. As I add more and more mass onto the friction box, there is less and less available contact area to expand into. In a sense, the contact area becomes saturated.
I suppose that if I kept piling on the weight, the friction force would eventually level out and stop increasing. This really isn't a big deal. The Amontons' Law isn't a law at all ok - it depends on your definition of Law. It's just a model. Let me give an example. Gravitational Model. Near the surface of the Earth, we can calculate the gravitational force on an object using the following model. The g vector is the local gravitational field. On Earth, it points "down" and has a magnitude around 9.
We often call this gravitational force the weight and it's a very useful model. Even though this model is useful, we still know it's wrong. The above gravitational model says that it doesn't matter how high above the surface of the Earth you are, the weight is the same.
We usually think of the normal force as opposite to weight by following the Newtonian action-reaction pair. So higher the mass or weight of the object higher will the reaction or normal force generated. Frictional force or opposing force is a force that opposes two objects sliding against each other, and it acts as a contact force like the normal force. While the normal force acts perpendicular to the flat surface, friction acts in a direction which is along the flat surface of an object.
Coefficient of friction The force of friction depends upon the coefficient of friction of the surface. The greater is the coefficient of friction of the surface the more is the force required to move it over that surface. A low value of the coefficient of friction indicates that the force required to slide the object is less than the force required when the coefficient of friction is high. Answer: Friction, force that resists the sliding or rolling of one solid object over another. Frictional forces, such as the traction needed to walk without slipping, may be beneficial, but they also present a great measure of opposition to motion.
Question 2: What are the two advantages and disadvantages of friction? Answer: Friction produces unnecessary heat leading to the wastage of energy. The force of friction acts in the opposite direction of motion, so friction slows down the motion of moving objects. Forest fires are caused due to the friction between tree branches. Question 3: What are the causes of friction? Answer: Friction is a resistive force, which comes into play when there is a relative motion between two bodies in contact.
The frictional force between two bodies depends mainly on three factors: I the adhesion between body surfaces ii roughness of the surface iii deformation of bodies. Question 4: What is streamlined shape explain with example? Answer: A special shape of the body that reduces fluid friction is called the streamlined shape.
Example: Aquatic animals like fish, crocodiles, and sharks and the vehicles like cars, flights, ships act. Streamlined shapes help reduce the amount of air drag when an object is moving.
Question 5: Does friction depend on the surface area? Answer: Friction is a contact force when two surfaces interact. Hence, so friction depends on the surface of contact as the surface of contact increases the frictional force also increases. Question 6: Find the force of friction if the coefficient of friction is 0. Skip to content. Solids Struct. Heterogeneous Media, Phys. Teidelt, E. Starcevic, J. Von der Nanotribologie bis zur Erdbebendynamik , Berlin: Springer, Book Google Scholar. Paggi, M.
Grzemba, B. R , , vol. Sivebaek, I. Hyun, S. Pohrt, R. Lett , , vol. Greenwood, J. Dimaki, A. Download references. Berlin University of Technology, Berlin, , Germany. You can also search for this author in PubMed Google Scholar. Correspondence to V. Popov, , published in Fizicheskaya Mezomekhanika, , Vol. Reprints and Permissions. What does friction really depend on?
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