Calculators/Physics/Projectile motion

Projectile motion

Range · maximum height · flight time · trajectory

Projectile motion — illustration
Range
40.77
m
Max height
10.19
m
Flight time
2.88
s
vₓ (constant)
14.14
m/s
Trajectory (parabola)
x [m]

g = 9.81 m/s². Maximum range at α = 45° (for h₀ = 0). The horizontal velocity vₓ is constant; the vertical one decreases by g each second.

Projectile motion is a combination of uniform horizontal motion and uniformly varying vertical motion. The initial velocity is split into the components vx=v0cos⁡αv_x=v_0\cos\alpha and vy=v0sin⁡αv_y=v_0\sin\alpha.

For a launch from ground level (h0=0h_0=0):

tflight=2v0sin⁡αgR=v02sin⁡2αghmax=v02sin⁡2α2gt_{flight}=\frac{2v_0\sin\alpha}{g}\quad R=\frac{v_0^2\sin2\alpha}{g}\quad h_{max}=\frac{v_0^2\sin^2\alpha}{2g}

The greatest range is given by an angle of 45°. The calculator also handles a launch from a height h0>0h_0>0 (and horizontal projectile motion as α=0\alpha=0), and it draws the trajectory with the highest point marked.

Examples

v₀ = 20 m/s, α = 45°
→ range ≈ 40.8 m, h_max ≈ 10.2 m, time ≈ 2.88 s
v₀ = 20 m/s, α = 30°
→ range ≈ 35.3 m (smaller than at 45°)

Frequently asked questions

Why does 45° give the greatest range?+

Because the range depends on sin(2α), and that function reaches its maximum at 2α = 90°, i.e. α = 45° (for a launch from ground level).

What happens to the horizontal velocity?+

It stays constant for the whole flight — no force acts horizontally (ignoring air resistance). Only the vertical component changes, slowed and then accelerated by gravity.

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