Open Day at the Sports Science Lab
1Each fall, the sports science lab at Brightwater University opens its doors to local middle schools. The lab studies how athletes move, from sprinters to basketball players. This year eighth graders Ottoline Baptiste and Kwame Esposito joined two stations, along with their physical education teacher, Mr. Ferdinand Oduya. At each station a lab assistant asked them to model how energy is stored as an athlete or a ball moves away from Earth and back again.
2The assistant explained that a runner and Earth pull on each other, so together they form a system. Energy is stored in this system, and the amount depends on the distance between the runner and Earth. The lab's software uses this rule: stored energy in joules (J) = mass in kilograms (kg) × 10 × height in meters (m).
3At the first station, each person ran up the stadium steps from the field and stopped at a numbered row. Each row is 0.4 m higher than the one below it. Ottoline climbed first, stopping at row 10 and then at row 20, while Kwame and Mr. Oduya each made one climb. A large screen beside the field showed the stored energy compared with the field (Table 1). A second screen at the concourse, a wide walkway level with row 10, showed the stored energy compared with the concourse instead. When Ottoline stood at row 20, the field screen read 4,000 J, but the concourse screen read 2,000 J.
4At the second station, a player tossed a 0.60 kg basketball straight up from her hands. A high-speed camera filmed the toss in front of a wall marked in centimeters, and the software worked out the ball's height above her hands and its speed in five frames (Table 2). The camera took hundreds of pictures each second, and the assistant picked five of them, from the moment the ball left the player's hands to the top of the toss. Air pushed on the ball so little that the lab ignored it.
5Before the students left, the assistant asked them to compare the two stations and to explain what the stair runs and the toss have in common. For each station, they also had to name the two objects that made up the system.