1953 AMC 12 第 10 题

Question

一个圆心固定、外径为

6

英尺的车轮，要使轮缘上的一点移动一英里，车轮需要转动的圈数为：

The number of revolutions of a wheel, with fixed center and with an outside diameter of

6

feet, required to cause a point on the rim to go one mile is:

880

\dfrac{440}{\pi}

\dfrac{880}{\pi}

440\pi

以上答案均不正确

none of these

车轮每转一圈，轮缘上的点移动一个圆周长

In one revolution the rim point travels one circumference

用

5280

英尺除以圆周长

6\pi

英尺

Divide

5280

feet by the circumference

6\pi

feet

车轮的周长为

6\pi

英尺，所以所需圈数为

\frac{5280}{6\pi}=\frac{880}{\pi}\text{。}

因此，正确答案是 C。

The wheel’s circumference is

6\pi

feet, so the required number of revolutions is

\frac{5280}{6\pi}=\frac{880}{\pi}.

Thus, the correct answer is C.

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