It is necessary to search for new sources of energy because the sources we have now are non-renewable and exhaustible. The usage of these sources are increasing day by day and if this continues then one day we wlii be left with none so it is necessary to search for new sources of energy
Work is equal to the force applied times the displacement. Since you pull the wagon at constant speed this means that there is no acceleration on the wagon as it does not change speed. F=ma. Since a=0, F=0. Therefore no work has been done in this situation
