You are an industrial engineer with a shipping company. As part of the package-handling system, a small box with mass 1.20 kg is placed against a light spring that is compressed 0.280 m. The spring, whose other end is attached to a wall, has force constant k = 45.0 N/m. The spring and box are released from rest, and the box travels along a horizontal surface for which the coefficient of kinetic friction with the box is μk = 0.300. When the box has traveled 0.280 m and the spring has reached its equilibrium length, the box loses contact with the spring.

What is the speed of the box at the instant when it leaves the spring?