A 3.8 kg box is sliding down a surface that is inclined downwards by 30° below the horizontal. Initially the box is at rest, and after sliding down by a distance of 1 m along the surface the box reaches the level floor. When the box just reached the level floor, the speed of the box is measured to be 0.8 m/s. How much energy of the box has been lost (dissipated) by the friction?