The Physics Factbook
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The static frictional force is the force that opposes the intended motion of two objects in contact. This force is equal to the coefficient of friction (µ) times the normal force(N).
f = µN
The value of µ depends on whether or not the object is in motion. µ static is usually higher than µ kinetic.
The angle inclination is found using …
θ = sin-1 (a/g)
Start with Newton's second law of motion …
Fnet = ma = 0
W//–f = 0
mg sin θ–µmg cos θ = 0
mg sin θ = µmg cos θ
sin θ = µ cos θ
tan θ = µ
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Manuel Caban, Whitney Daniel, Alex Grisales -- 2005Students Choice pages in The Physics Factbook™ for 2005
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