Bowing effect on energy conservation in an incline experiment

Incline experiments with a car travelling down dynamic track are performed to demonstrate mechanical energy conservation under the assumption that there is no friction. Data analysis revealed cases when mechanical energy seems to increase as the car travels down incline, contradictory to the expectation. A detailed examination leads to the conclusion that this is caused by the slight downward bowing of the dynamic track, the details of which are reported here. This result provides an explanation to the seemingly contradictory result. It can also be used to stimulate students to perform in-depth data analysis.