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Grades K–2 · Organisms

How does a duck paddle without a paddle?

A duck may glide across a pond while its feet work below the water. Skin joins its toes. When a foot spreads out, it makes a broad little paddle.

O61 visual explanationA schematic duck spreads a webbed foot and pushes water backward; the water pushes the duck forward. No swimming speed, lift contribution or complete stroke force is calculated.A broad foot can push water backwardSpread footWater backwardDuck forwardA broad foot pushes; a folded foot comes forward.

In the diagramA broad foot can push water backwardSpread footWater backwardDuck forwardA broad foot pushes; a folded foot comes forward.

The spread webbed foot pushes water backward, and water pushes the duck forward. Bringing the toes closer changes the foot's surface for the return stroke.

During a pushing stroke, the broad foot pushes water backward. The water pushes back on the foot, helping move the duck forward. To bring the foot forward for another stroke, the duck draws its toes closer together. A narrower foot presents less broad surface to push against the water on the way back.

The foot spreads for a push and narrows for a return, over and over. Its shape and position change through the stroke. Above the surface, the duck may seem to slide smoothly. Below it, changing feet keep exchanging pushes with the water.

About this explanation

Starting knowledge: Recognize forward and backward movement.

Sources

  • Scientific Reports — The hydrodynamic performance of duck feet for submerged swimming resembles oars rather than delta-wings
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