Hanging in the BalanceAlbert LiAward: Top 100
School: los altos high school The image displays a basketball player in equilibrium while hanging on the rim. First, the weight of the player is evenly split in the tension of his arms, each arm carrying half the load. This allows the player to more easily balance himself on the rim. However, there is deception within the image. The tension in the arms is supported by the rim, and the rim is supported by the backboard. In the image, the rim appears flat, because the photo was composed from a worm's-eye view. However, the rim must have a slight bend once the player hangs. The bend creates a pivot point where the part of the rim across from the player's position is welded to the rectangular connector to the blackboard. Now, torque becomes a factor. The torque is the cross product of the player's weight and the sine of the angle formed by the rim's bend and the backboard. This torque pulls downward on the connector, and it must be opposed by an equal and opposite torque exerted by the backboard to keep the connector piece stable. Conversely, the opposing torque is the cross product of the connector's diameter and the upward force of the backboard. Since the connector's diameter is much smaller than the rim's, the backboard must impose a much larger force than the player's weight. Although the net force of the system is zero, the physics tells us that there are still many forces battling under the surface. 
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