With the 2012 Summer Olympics well under way in London, the eyes of the world are watching the extreme athleticism exhibited by the competitors. But in addition to sports skills, the Olympians competing this year can be considered practical physicists, as well.
After all, to win a swim race by fractions of a second, or spin around four times after bouncing off a vault, the ability to harness physics principles such as angular momentum and hydrodynamics is as important as muscle memory and strength.
Some of the Olympic sports where physics makes all the difference:
Olympic swimming races are often decided by tenths or hundredths of a second. With a margin like that, the tiniest details that affect a swimmer's speed can make the difference between winning and losing. Swimmers must do everything they can to reduce the water resistance against their body as they propel forward.
Resistance will increase with the surface area exposed to the water, so the more streamlined a swimmer can make her body, the quicker she will go. The smoother this surface is, the better, as well. That's why swimmers often shave all their body hair, wear swim caps to cover their heads, and cover much of their bodies with specially designed swimsuits that mimic shark's skin or other surfaces for greater hydrodynamics.
Swimmers must also think about buoyancy, the force that keeps them afloat. Because water is more resistant to movement than air, it is in athletes' best interests to swim as close to the surface as possible so that more of their bodies are exposed to the less resistant air than to the dragging water.
The principle of angular momentum is immediately apparent when watching Olympic gymnasts spin and twirl, aiming to win higher scores by packing in more rotations.
All objects spinning around a point have a quantity called angular momentum that depends on the object's mass, speed and how spread out it is around its center of gravity. Unless some outside force interferes with the system, its angular momentum will be conserved. Thus, a gymnast can spin faster by pulling in his arms and legs as tightly as possible, thus reducing the space over which his mass is spread out. In response, the gymnast's speed will increase to make up the difference and keep his total angular momentum constant.
Newton's third law of motion also plays a great role in gymnastics. The law states that for every action, there is an equal and opposite reaction. Gymnasts take advantage of this by pushing hard against the floor, the balance beam or the vault, so that these surfaces push back hard against them, giving them lift into the air.
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