Article

Horizontal throw

Leave an edge with speed only in x. Flight time comes from the fall; range from constant vx.

Part 5 of Physics without mysteries. Comparison: throw hub.

How it works

In a horizontal throw v0 has only an x component. Vertically you start at zero speed and fall a height h: t = √(2h/g). Horizontally you cruise at constant v0, so Z = v0·t.

It is the angled-throw limit as α → 0° from a height. If someone gives an angle and h0, use full projectile motion instead of forcing the simplification.

Bridge example: h = 20 m, v0 = 10 m/s → t ≈ 2.02 s and Z ≈ 20.2 m (g = 9.81). School problems ignore air drag.

Which formula when

QuantityFormulaSource
Flight timet = √(2h/g)Vertical fall with vᵧ₀ = 0
RangeZ = v₀·tConstant vₓ = v₀
Pathy = h − ½gt², x = v₀tParabola in the plane
α = 0, h₀ > 0full projectile modelWhen you also want landing vᵧ

Solved problems

From a bridge

From a bridge of height h = 20 m you throw horizontally at v0 = 10 m/s. Take g = 9.81 m/s². Find flight time and range.

Steps

  1. Time from fall: t = √(2h/g) = √(40/9.81).
  2. t ≈ √4.077 ≈ 2.02 s.
  3. Range: Z = v₀·t = 10 · 2.02 ≈ 20.2 m.
  4. vₓ is constant; vertically it is ordinary fall with vᵧ₀ = 0.
  5. Fill the horizontal-throw calculator: v₀, h, g.

Answer: t ≈ 2.02 s, Z ≈ 20.2 m

Fill in the calculator