1. The problem statement, all variables and given/known data An athlete whose mass m is performing weight lifting excersies. Starting from rest positions, he lifts, with constant acceleration, a barbell that weighs w. He lifts the barbell a distance of x in time of t. Use Newton's laws to find the total force his feet exert on the ground as he lifts the barbell. 2. Relevant equations F=ma 3. The attempt at a solution I drew the free body diagram already, with the force his feet exert on the ground downward, the normal force upward, and the gravity force downward. Is this correct? Is there any other force I'm missing?