ScienceShot: Whoa Nellie! Slow Down on That Turn

Dogs may be man's best friend, but when it comes to racing, we have a lot more in common with horses. By measuring the positions and speeds of horses during two competitive polo matches and 56 races, researchers have found that horses, like people, slow down when rounding a bend. All animals, when turning a corner, need to generate a force that is at a right angle to their forward motion. Otherwise they slide outwards. Dogs shift the force onto their front legs, leaving their back legs free to continue to power their forward motion. But horses, like humans, are unable to shift their weight off all four legs; they compensate for the additional force by keeping their feet on the ground longer. This creates friction and slows the animal down, the team reports online today in the Proceedings of the Royal Society B. If a horse wants to move faster, it needs to cut corners.

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