Awood block, after being given a starting push, slides down a ramp at a constant speed. what is the angle of the ramp above horizontal? suppose that μk = 0.2.

Refer to the diagram shown below.

μ = 0.2. the coefficient of dynamic friction
N = mg cosθ, the normal reaction
μN = μmg cosθ, the frictional force resisting motion down the inclined plane.
mg sinθ = the force driving the block down the inclined plane.

Because the block slides down the inclined plane with constant velocity, it is in dynamic equilibrium.
Therefore
mg sinθ = μmgcosθ
tanθ = μ = 0.2
θ =tan⁻¹ 0.2 = 11.3°

11.3°

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