I am practicing using the simulation tools for a device Im working on for an internship. I made a simple non linear dynamic simulation where a steel ball hits a thin walled steel box at 100m/s. the ball did not seem to slow down when bouncing off of the box so i plotted the velocity of the ball and the point on the box where the ball hits,  and the final velocity after bouncing is 140m/s

whaiiiii?