Races between moving objects are an engaging way to teach dynamics to introductory physics students. One standard example consists in racing hollow and solid cylinders as they roll down an inclined plane. Another striking demonstration is a race between two marbles on side-by-side tracks that start and end together, but with one track taking a straight path and with the other following a cycloidal shape. In the present article, two objects (having the same mass and shape) are launched from the same starting height with the same speed up an inclined plane. One of the objects is subject to kinetic friction. The other object is not because it rolls without slipping on wheels along the incline with negligible rolling friction. Each object travels upward, slows down, and then turns around and retraces its path to its starting point. If the two objects are launched simultaneously, which one makes it back first?

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Use a T10 star screwdriver to disassemble the cart. (The PASCO manual incorrectly says to use a number 1 Phillips screwdriver.) Remove the plunger assembly, the two magnets, and the four large nuts.
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The zero position is measured immediately after each experimental run, to account for changes in the spring compression when the track angle is varied, as well as to account for any shifts in position of the motion detector, track, or spring stops during the firing and subsequent motion of the cart.
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Equation (8) has a minimum at /tan = 0.3966 corresponding to = 26.76° for the blue curve in Fig. 4.
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Since the two carts move at different average speeds, the energy loss will be slightly different for the two carts.
11.
Three videos showing races between the rolling and sliding carts are available online at TPT Online under the Supplemental tab, http://dx.doi.org/10.1119/10.0004147.