Physics en PointeAliza WelnerAward: Top 100
School: frisch school My photo features my sister balancing en pointe, inspired by the fact that I have been dancing en pointe for four years. Due to the combination of gravity and surface area, these beautiful shoes are extremely uncomfortable! In normal gait, the force of my body (mass multiplied by gravitational acceleration) is distributed over both feet. When I first began ballet, I learned to pirouette on the ball of my foot (demi pointe). Doing so divides the surface area for weight distribution in half, which makes it more difficult to oppose the force of gravity that may pull me off balance. After years of strength building, dancing on demi pointe became almost as natural as walking because I gained the strength to hold up my weight over a smaller surface area. However, when I put on my pointe shoes, I nearly quarter the surface area. All of the weight is centered on a one by two inch surface area, which forces all of my weight onto my toes. As shown in this photo, the ballerina is balancing on a smaller surface area when en pointe which increases the pressure on her toes (pressure equals the force divided by the area). Additionally, due to the lower surface area en pointe, the ballerina constantly shifts her center of mass to maintain balance over her toes, countering her inertia as she moves through her dance. 
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