有没有人帮忙翻译一段东西呀？
[size=3]in baseball, the home run is a sure way to score and the problem of hitting the ball as far as possible is as old as the game.
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[size=3]An analysis of the problem consists of two phases:impact and flight.Many previous investigations have considered one or both of the phases of this problem.
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[size=3]Briggs investigated the effects of velocity and spin on the lateral deflection of a curve ball. Baseballs spinning about a vertical axis were dropped through a horizontal wind tunnel.
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[size=3]The lateral deflection of the ball was found to be proportional to the spin and the square of the translational velocity for speeds up to 150 ft/s and spins up 1800 rpm.
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[size=3]Achenbach characterized the drag on spheres as a function of the Reynolds number Re and the surface roughness. He shouwed that there is a [/size]
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[size=3]critical Reynolds number at which the drag coefficient Cd decreases dramaticall and that this critical Reynolds number decreases as the roughness increases .
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[size=3]Although a baseball is not uniformly rough, the spinning seams cause boundary layer behavior similar to that of a rough surface[/size]