
Classical Mechanics30
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F = −kΔx. (2.9)
The constant of proportionality k is called the spring constant and is dependent on the properties
of an elastic body, and Δx is the extension or compression of the spring from its relaxed position.
Friction forces play a crucial role in damping or retarding motion initiated by other forces. The
friction force between two contact bodies results from the interaction between the surface mol-
ecules of the two bodies and involves a very large number of such interactions. The phenomenon
is therefore complex and depends on factors such as the condition and nature of the surfaces ...