1. The problem statement, all variables and given/known data Q: A boy falls with the acceleration 4g in a free fall until he hits a net. His mass is 78kg. You can ignore other forces. With what force does he influence the net? 2. Relevant equations F=m*a 3. The attempt at a solution I use the formula F=m*a which gives med 78kg*4*(9.82m/s2)=3,1kN. My teacher did though tell me that the answer were 3,9kN, but i can't figure out what formula to use then. What have i missed?