Coefficient of Friction

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Coefficient of Friction- Post Lab Abstract The purpose of the experiment was to determine to coefficient of friction on a block sliding across a horizontal plane, and on the same block sliding down an inclined plane. This was done by first testing block, and how much weight on a string was needed to move the block at a constant velocity using a pulley system. The block weighed 0.2385 kilograms, and needed a hanging mass of 0.05 kg to move at a constant velocity. This means the coefficient of friction is 0.37. The second block was tested on an inclined plane, and the angle was found at which the block would move at a constant velocity. The angle found was 230. Using the equation μk=tan θk we found the friction to be 0.42. The friction was different because there was more force required to keep the block sliding down the plane at a constant velocity. Introduction Frictional forces are universal, in which they are found between two solid surfaces in parallel contact. If an object moves over a surface, the force exerted on the object by the surface is called the Kinetic friction force. This force is in a direction opposite the direction the object is moving. The friction force is proportional to the normal force exerted by the surface on the body. The force’s relationship can be viewed by using the coefficient of kinetic friction, μk, in f=μkn, where f is the magnitude of the force of the friction, and n is the magnitude of the normal force. If the surface is flat, and horizontal, the normal force is equal to the weight of the object, due to the fact that because there is no acceleration in the normal direction, there is no net component in the opposite direction. If the surface is sloped, the normal force is the component of the weight, which is perpendicular to the surface. If the object is pulled over the surface at a dynamic equilibrium (constant
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