Horizontal projectile: fall time and range

A ball is thrown horizontally at 5 m/s from a height of 20 m (g = 10). Find the fall time 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 = 5×2 = 10
   Uniform horizontal motion at constant velocity

Why it works

The vertical and horizontal motions are independent. Vertically it is free fall, so the height alone fixes the time; horizontally the speed is constant.

Common mistakes

• Mixing the initial speed into the fall time (the horizontal speed does not affect fall time).
• Forgetting to convert units before calculating.

Related

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