Two coal carts, A and B, started simultaneously from opposite ends of a 400-yard track

题目

Two coal carts, A and B, started simultaneously from opposite ends of a 400-yard track. Cart A traveled at a constant rate of 40 feet per second; Cart B traveled at a constant rate of 56 feet per second. After how many seconds of travel did the two carts collide? (1 yard = 3 feet)

选项

解析

我们先从同时涉及两车（A车和B车）的文字等式入手。由于赛道长400码，可列出：**A车行驶的距离 + B车行驶的距离 = 400码** 因为速度的单位是英尺/秒，所以我们要把400码换算成1200英尺。此时文字等式变为：**A车行驶的距离 + B车行驶的距离 = 1200英尺** 设\( t \)为A车的行驶时间（单位：秒），那么\( t \)也是B车的行驶时间。根据公式：**距离 = 速度×时间** 将相关数值代入等式，得到：\( 40t + 56t = 1200 \)英尺化简：\( 96t = 1200 \) 求解：\( t = 1200÷96 = 600÷48 = 100÷8 = \frac{25}{2} \)（秒）答案：D

在线客服

官方微信

公众号