This is the first of two questions about net impulse during a vertical jump. Austin (75.9 kg body mass) is recovering from knee surgery and is doing testing to be cleared to return to sport. One of the evaluations is a vertica jump on a force plate which gives ground reaction force. The data show that they stood motionless for 1 s then initiated the counter-movement jump. Vertical ground reaction force was reduced to 75.5% of body weight for 0.55 s during the counter movement. Vertical ground reaction

This is the first of two questions about net impulse during a vertical jump. Austin (75.9 kg body mass) is recovering from knee surgery and is doing testing to be cleared to return to sport. One of the evaluations is a vertica jump on a force plate which gives ground reaction force. The data show that they stood motionless for 1 s then initiated the counter-movement jump. Vertical ground reaction force was reduced to 75.5% of body weight for 0.55 s during the counter movement. Vertical ground reaction