1. The problem statement, all variables and given/known data During Operation the jack hammer develops on the concrete surface develops a force @ t=0 f=0, @ t=.2, F=90, @ t=.4, F=0. Graph looks like a triangle To achieve this the 2lb spike S, is fired from rest into the surface @ 200ft/s. Determine the speed of the spike just after rebounding 2. Relevant equations mv + E Fdt=mv 3. The attempt at a solution Well it seems to me that the initial velocity is 0, and the final is 200ft. How do i know the rebound velocity.