[{{ 183_notes:mi3e_04-024.png?200|Start pushing a brick on a table and the atoms rearrange a bit; they resist the motion}}]
[{{ 183_notes:mi3e_04-024.png?200|Start pushing a brick on a table and the atoms rearrange a bit; they resist the motion}}]
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Friction is a resistive force that is due the contact between two objects. While the normal force is perpendicular to the contact surfaces, the frictional force is parallel. So, the vector sum of these two forces (when both are acting) is the force that the surface exerts on the object. That is, both the normal and frictional forces are due to the same contact interactions, they are often just separated into parallel and perpendicular components to the surface for convenience.
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Friction is a resistive force that is due the contact between two objects. //While the normal force is perpendicular to the contact surfaces, the frictional force is parallel.// So, the vector sum of these two forces (when both are acting) is the force that the surface exerts on the object. That is, both the normal and frictional forces are due to the same contact interactions, they are often just separated into parallel and perpendicular components to the surface for convenience.
[{{183_notes:asperities.png?200|The roughness of two materials in contact shown at the microscopic level. }}]
[{{183_notes:asperities.png?200|The roughness of two materials in contact shown at the microscopic level. }}]