A particle of mass 2.5 kg moves along the x-axis. It moves away from the origin under the action of a force directed toward O. The magnitude of the force is (2r + 3) N. When x=0 m, the speed of the particle is 1.5 m/s. Fill in the blank. When v = 1.0 m/s, the positive value of x, to one decimal place, is m.

A particle of mass 2.5 kg moves along the x-axis. It moves away from the origin under the action of a force directed toward O. The magnitude of the force is (2r + 3) N. When x=0 m, the speed of the particle is 1.5 m/s. Fill in the blank. When v = 1.0 m/s, the positive value of x, to one decimal place, is m.