Verified answer

F(friction) = μN

F(friction) = μ(mgcosθ)

μ = F(friction)/(mgcosθ)

μ = 4.05 /(3*10*cos65) = 0.319

For constant velocity, F(net) = 0

F(net) = F(weight component along plane) - F(friction)

F(weight component along plane) = F(friction)

mgsinθ = μN

mgsinθ = μmgcosθ

tanθ =μ

tanθ = 0.319

θ = 17.7°

3*g*cos(65°)*coefficient = 4.05 N

b) At what incline (measured in degrees) will the box slide at a constant velocity?