(2013?Binzhou model) shown in the figure, the object A, B with a thin rope connected to the spring across the pulley, A is stationary in the inclination of 45 ° of the rough inclined plane, B hanging

Set mA = 3mB = 3m, the object B force analysis, by gravity and tension, by the balance of forces: T = mg, then know the spring force is unchanged.

And then the object A force analysis, by gravity, support, tension and static friction, as shown in the figure

Based on the conditions of equilibrium to get

f + T-3mgsinθ=0

N-3mgcosθ=0

Solve

f = 3mgsinθ - T = 3mgsinθ-mg

N=3mgcosθ

When θ becomes small, the static friction f on object A decreases, and the pressure N on the inclined plane increases; therefore, C is correct and ABD is wrong.

So choose C.