Projectile Motion Explained
Projectile motion combines independent horizontal motion with vertical free fall. Understanding this split makes predicting range, time of flight, and trajectory straightforward.
Independent horizontal and vertical motion
Once launched, the horizontal velocity stays constant (ignoring air resistance) while gravity accelerates the object downward. Neither motion affects the other.
The parabolic path
Combining constant vx with accelerating vy traces a parabola. Launch angle and initial speed determine the maximum height and horizontal range.
Try it in the lab
Open the projectile simulation, set launch speed and angle, press Play, and read live vx, vy, range, and time of flight as the object moves.
Free Fall & Projectile Motion
Drop anything — a coin or a bowling ball — and gravity speeds it up at exactly the same rate, so they hit the ground together. Toss something sideways instead, and it still falls straight down just as fast, because its sideways motion and its falling motion don't affect each other at all.
h = ½ · g · t²
- h — height fallen (m): how far the object has fallen from its starting point
- g — gravitational acceleration (m/s²): how quickly falling speed increases each second — the same for every object
- t — time (s): how long the object has been falling
A ball is dropped from rest and falls for 2 seconds. How far has it fallen? (use g = 9.8 meters per second squared)
- t = 2 s
- g = 9.8 m/s²
- h = ½ · g · t²
- h = 0.5 × 9.8 m/s² × (2 s)²
h = 19.6 m