(2013?Huizhou second model) A small ball of mass m is bolted to a thin rope, which compresses a light spring fixed on the wall by x. The ball is not attached to the spring. As shown in the figure

A, the rope will be burned off, the ball is subject to the ball's gravity and the spring's elasticity of the *** with the role of the combined force diagonally down to the right, not only the role of gravity, so it is not a parabolic motion, so A error.

B, the ball off the spring, only by gravity, do uniform velocity motion, so B is correct;

C, the moment the rope burned off, the ball by gravity and spring elasticity, the combined force slanting down to the right, then so the acceleration is not g, so C is wrong.

D, according to the kinetic energy theorem, mgh + W =

1

2

mv2. The kinetic energy of the ball when it hits the ground is greater than mgh, so D is wrong.

Therefore, choose B.

.