A \( 0.4 \, \text{kg} \) mass takes \( 8 \, \text{s} \) to reach ground when dropped from a certain height ‘\( P \)’ above surface of earth. The loss of potential energy in the last second of fall is ______ \( \text{J} \). (Take \( g = 10 \, \text{m/s}^{2} \))