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Why does a rugby ball's flatter ends make it travel differently (through
the air) than a football, when they are almost the same otherwise?
A football and a rugby ball are quite similar in shape and size. Both
balls are oval and are 11 inches long. The difference between the two is
the shape balls' ends. The football has ends that come to a point--while
the rugby ball has flatter ends. The ends of these balls make a significant
difference in how each moves through the air.
The football has a more streamlined design and consequently has less
drag--allowing the ball to move more easily through the air. The rugby ball,
with its flat ends, has more drag as it is passed from player to player
through the air. There is more drag on a rugby ball traveling at the same
velocity as football. The rugby ball is also more prone to tumbling end
over end--an extremely inefficient way of traveling.
The differences in the way the two sports are played take advantage of
the design of each particular ball. The optimal way to pass a football is
in an overhand motion that creates a "spiral"--this gyroscopic
motion makes the ball more stable in flight. The stability of the football's
flight allows players to execute plays that require pinpoint passes and
precision timing. It also allows some players to throw the ball 70 yards
In rugby, the passes are generally shorter and are executed with an underhand
motion. The ball retains some stability in flight on short passes, but tumbles
end over end in longer passes or kicks.