Horizontal throw from 20 m at 10 m/s

A ball is thrown horizontally at 10 m/s from a height of 20 m (g = 10). Find the time of flight and the horizontal distance.

Step-by-step

1. t = √(2h/g) = √(2×20/10) = 2
   Free fall vertically: the time to land depends only on the height
2. x = v₀t = 10×2 = 20
   Uniform horizontal motion at constant velocity

Why it works

The two directions can be handled separately: the fall time follows from the height through h = ½gt², and the horizontal distance is the unchanged horizontal speed times that time.

Common mistakes

• Combining the height and the horizontal speed into one speed.
• Thinking the growing vertical speed reduces the horizontal speed.

Related

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