7. Work and Energy Concepts

Twenty-four-year-old Jack Jones, a second-year orthopaedic resident, had been a track star in the decalthalon when he went to undergraduate school at Wichita State University. During medical school at the University of Kansas, he concentrated on the high jump, practiced nearly every day, and even competed in the 1996 Olympic Games tryouts. He trained constantly, running sprints and jumping when the pit was available. But on becoming a resident with a more rigid and demanding schedule, he found it almost impossible to get in his daily workout and had to be content with a more erratic calendar of practicing. Sometimes he got up at 5 a.m. to work out and jump before early morning rounds at the hospital, or he worked out late at night after coming home from the hospital. Nevertheless, he did manage to train three or four times a week and thus burn up enough calories to allow him to cope with the hospital’s food and maintain a weight of 65 kg. In his high jump, he did work and consumed energy. How much potential energy could he convert to kinetic energy by just barely clearing the six-and-a- half-foot high bar?