Marker Tests After the Storm
After a strong storm, part of the baseball field was damp. The field crew tested a foam boundary marker before repainting the foul line. They pulled the marker with ropes in opposite directions and measured how far it traveled during each one-second interval. A force is a push or a pull. Forces in opposite directions can balance when they have equal strength.
The records show the marker's motion. In Test A, the marker started at rest on dry grass. The left pull was 5 units and the right pull was 5 units. It traveled 0 cm, 0 cm, and 0 cm during the first three seconds. In Test B, the marker was already moving right on dry grass. The left and right pulls were each 4 units. It traveled 6 cm during each of the three seconds.
In Test C, the marker started at rest on dry grass. The right pull was 7 units and the left pull was 3 units. It traveled 3 cm, 6 cm, and 9 cm during the first three seconds. In Test D, the marker was moving right. The left pull was 7 units and the right pull was 3 units. It traveled 9 cm, 6 cm, and 3 cm during the first three seconds.
The crew then compared surfaces. In Test F, the marker was moving right at the same starting speed on dry grass. The pulls were 4 units left and 4 units right. It traveled 5 cm in each second. In Test G, the starting speed and pulls were the same, but the marker moved on the storm-damp grass. The wet grass rubbed on it, and it traveled 3 cm, 2 cm, and 1 cm. The crew kept the marker and rope pulls the same so the surface would be the main change.