(20 13? Changchun simulation) an object with a mass of 2kg moves at a uniform speed on a rough horizontal plane under the action of horizontal constant tension, when

So μ = ffn = 6 mg = 620 = 0.3, so A is correct;

B, the area enclosed by the image and the coordinate axis represents the work done by pulling force, so we can know from the image that WF = (6× 4+12 )×1j = 36j (square number), and the work done by sliding friction WF =- micron GX =-6×1kl.

C, according to the kinetic energy theorem:

0- 12mv2 = W。

Solution: v=30m/s, so C is correct;

D, because we don't know the specific motion of the object, we can't calculate the time, so D is wrong.

Therefore: ABC ..