Projectile motion

Science

Definition

Projectile motion is the curved path an object follows when launched near Earth's surface and affected only by gravity. The horizontal and vertical components of motion are independent — horizontal velocity stays constant while vertical velocity changes due to gravitational acceleration.

How It Works

  1. Resolve the initial velocity into horizontal (vx = v₀cosθ) and vertical (vy = v₀sinθ) components.
  2. The horizontal component remains constant throughout the flight (no air resistance).
  3. The vertical component changes due to gravity (a = −9.8 m/s²).
  4. Use kinematic equations separately for each direction to find position and velocity at any time.
  5. The object hits the ground when vertical displacement returns to zero.

Examples

  • A basketball following an arc from a player's hands to the hoop
  • A cannonball launched at an angle from a cliff
  • A ball kicked off a table falling in a parabolic curve
Key Fact

Range = (v₀²sin2θ)/g; maximum range occurs at θ = 45°

Related Terms

Kinematic equations Acceleration Displacement and velocity Free-body diagrams

Study This Concept

Practice projectile motion with free review games in these units:

AP Physics 1 Unit 1: Kinematics Physics Unit 1: Motion and Kinematics