There two problems related to this problem:
First is the coefficient of static friction between the map
and the crate.
And the second one is at what angle does the crate begin to
slide if the mass is doubled.
1.
To look for the coefficient of static friction:
ΣF = 0
μ x m x g x cos θ = m * g * sin θ
μ = sin θ/ cos θ = tan θ
μ = tan 24 = 0.45
2.
At what angle… the solution is:
The static friction or μ does not depend
on mass, so the angle is still 24.