Passage III

In 5 trials, a toy cart rolled on a track after being released from rest at Point S (see Figure 1).

For each combination of cart mass, M, and loop radius, r, Point S was at the minimum height, h, required for the cart to roll completely through the loop. The cart was stopped at Point V.

The cart's gravitational potential energy, PE, at Points S and U and the cart's kinetic energy, KE, at Point U are shown in Table 1. When the cart was on the floor, PE was zero. The cart's total mechanical energy, TME, at a given point equaled PE + KE at that point. TME at Point S minus TME at a second point equaled the amount of TME converted to heat by friction between Point S and the second point.

Figure 1 and Table 1 adapted from T. M. Cooney, D. F. McGrail, and R. D. Unruh, eds, Physics Resources and Instructional Strategles for Motivating Students. @1993 by The College of Natural Sciences, The University of Northern lowa.