Resists sliding; static friction is up to μsN and kinetic friction is μkN.
Dry friction is bounded: F≤μsN before slipping and F=μkN during sliding, μk usually less than μs. The friction angle φ=atan μs. Applications: wedges, belts, brakes, screws.
A 50 kg crate with μs=0.4 needs about 196 N to start moving.
Friction decides whether objects slide, how brakes work and why a ladder does not slip, so it is part of almost every practical design.
Resists sliding; static friction is up to μsN and kinetic friction is μkN.
Friction decides whether objects slide, how brakes work and why a ladder does not slip, so it is part of almost every practical design.
Static friction adjusts up to a maximum of mu s times N to prevent sliding. Once sliding starts, kinetic friction takes a lower, roughly constant value of mu k times N.
In the basic model it does not. The friction force depends on the normal force and the coefficient, not on the apparent area.
Typical applications include checking whether a crate will slide on a loading ramp, sizing a brake pad for a required stopping force and designing a clamp that holds a part without slipping.
Study "Supports and reactions" first (topic 10 of 106 in Engineering Mechanics). It covers the groundwork this topic builds on.
Friction opposes impending motion. Independent of contact area in the basic model. Rolling resistance is much lower.
A 50 kg crate with μs=0.4 needs about 196 N to start moving.
The next topic is "Trusses", which builds directly on this one.
It is classed as Beginner in Engineering Mechanics (topic 11 of 106). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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