Hõõrdjõudude

Hõõrdjõud is the Estonian term for friction force. It is a force that opposes the relative motion or tendency of motion between two surfaces in contact. Friction arises from the microscopic irregularities and electromagnetic forces between the atoms and molecules of the surfaces. There are several types of friction, including static friction, kinetic friction, rolling friction, and fluid friction.

Static friction is the force that prevents an object from moving when a force is applied. It acts in the opposite direction to the applied force and its magnitude increases up to a maximum value, beyond which motion occurs. Kinetic friction, also known as sliding friction, acts on objects that are already in motion. It is generally less than the maximum static friction and is relatively constant as long as the surfaces and the normal force remain the same. Rolling friction occurs when an object rolls over a surface. It is typically much smaller than sliding friction. Fluid friction, or drag, is the resistance experienced by an object moving through a fluid like air or water.

The magnitude of friction force depends on the nature of the surfaces in contact, characterized by the coefficient of friction, and the normal force pressing the surfaces together. Friction plays a crucial role in everyday life, enabling us to walk, drive vehicles, and use tools. However, it can also be undesirable, causing wear and tear and energy loss in machinery, necessitating lubrication.