How energy is conserved in a given system

The goal of our lab was to measure how energy is conserved in a given system. In the beginning, we started to lunch the cart after taking the cart weight and we got m= o.999kg. Moreover, for the graph we took the relationship between the postion (s) and the time (s). Then we found the angle of the truck which was 11. Also, we found the Ei which was o.576J and the Ef which was 0.576J. We created the single graph with the results that we got. We found the lenst (look at the table below). Lastly, we got for the NE 0.057 and for N(&) 1.163 , and 1.000 for No. Also, we got 0.006 for E(segma). Overall, we had some errors like human and systematic, but the main error was of losing energy.