# Answer to Question #24566 in Mechanics | Relativity for Ali

Question #24566

When a horizontal of 30 N acts upon a 5 kg object on a surface the object moves with constant velocity. Find the coefficient of kinetic friction, between the object and the surface (gravity is equal to 10)

Expert's answer

The object moves with constant velocity, therefore its acceleration equals 0:

X-axis: F - F_fr = ma = 0 => F = F_fr.

F - a horizontal force& (30 N)

F_fr - friction force

Y-axis: N = mg &

F_fr = k*N & => F_fr = k*mg

k - the coefficient of kinetic friction

Therefore:

F = k*mg => k=F/(mg)

k=F/(mg) = 30/(5*10) = 3/5 = 0.6

Answer: the coefficient of kinetic friction equals 0.6

X-axis: F - F_fr = ma = 0 => F = F_fr.

F - a horizontal force& (30 N)

F_fr - friction force

Y-axis: N = mg &

F_fr = k*N & => F_fr = k*mg

k - the coefficient of kinetic friction

Therefore:

F = k*mg => k=F/(mg)

k=F/(mg) = 30/(5*10) = 3/5 = 0.6

Answer: the coefficient of kinetic friction equals 0.6

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