Answer:
fr = μ[tex]\miu _{k}[/tex] m g cos θ
the correct answer is less than fr = μ[tex]\miu _{k}[/tex] 2m g cos θ
Explanation:
Let's propose the solution of the problem to be able to answer the question, let's fix a reference system with one axis parallel to the plane (x-axis) and the other perpendicular, let's write Newton's second law
Y Axis
N - W cos θ = 0
N = mg cos θ
X axis.
fr - w sin θ = 0
fr = mg sin θ
the friction force is described by the expression
fr = μ N
fr = μ[tex]\miu _{k}[/tex] m g cos θ
When we analyze this expression we see that the friction force is equal to (μ_k m g cos θ)
If everything is well written in your problem, the correct answer is less, even though I think you have an error when writing the number