Cart Clues on the Snowy Forest Trail

A Cart on the Model Trail

At a snowy forest trail station, fourth graders built a small model trail from a smooth board. A wooden cart carried a cloth pouch of trail flags. At the end of the board, the cart pressed into a soft foam block that stood for a snowbank. The cart, pouch, board, foam block, starting line, and measuring tools stayed the same during the main test.

The class used a release gate to give the cart three different speeds. They did not push the cart by hand. A motion sensor recorded the cart's speed during the final half second before it reached the foam block. The class tested each release setting three times. At the slow setting, the sensor readings were 20, 20, and 20 centimeters per second. At the middle setting, the readings were 40, 40, and 40 centimeters per second. At the fast setting, the readings were 60, 60, and 60 centimeters per second.

After each cart reached the foam, students measured how far the foam block moved. At the slow setting, the block moved 3, 4, and 5 centimeters. At the middle setting, it moved 5, 6, and 7 centimeters. At the fast setting, it moved 10, 11, and 12 centimeters. Students used the average movement for each setting in the graph. The cart did not carry the pouch into the foam block; the pouch stayed attached to the cart.

The class wanted to know whether the cart's speed was connected to how strongly it affected the foam block. They planned to use the repeated measurements, not just one unusual result, when making a claim. They also knew that the test could show a pattern without telling the precise amount of energy in the cart.