Question

1. a bullet shot at 800. m/s horizontally hits a target that is 180. m away. how far does the bullet fall before it hits the target?
2. a student throws a ball (horizontally) out of a window that is 8.0 m above the ground. another student who was 10.0 m away caught it. what was the initial velocity of the ball?

Explanation:

Step1: 垂直方向運動分析

根據自由落體公式 \( h = \frac{1}{2}gt^{2} \)，其中 \( h = 8.0m \)，\( g = 9.8m/s^{2} \)，可求出時間 \( t \)。

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Step2: 水平方向運動分析

水平方向為勻速直線運動，公式 \( x = v_{0}t \)，已知 \( x = 10.0m \)，\( t\approx1.28s \)，求初速度 \( v_{0} \)。

$$ v_{0}=\frac{x}{t}=\frac{10.0}{1.28}\approx7.81m/s $$

Answer:

約 \( 7.81m/s \)