Projectile motion describes the curved, parabolic path an object takes when launched into the air. It’s analyzed by treating the motion as two independent components: a constant horizontal velocity and a vertical motion subject only to the acceleration of gravity.

What is Projectile Motion?

Projectile motion is the motion of an object thrown or projected into the air, subject only to the acceleration of gravity. This means we usually ignore air resistance in basic physics problems, focusing purely on the effect of gravity.

The path a projectile takes is called its trajectory, and it’s always a parabola (a curved shape).

Key Things About Projectile Motion

  • Two Independent Motions: Projectile motion can be broken down into two separate, independent motions:
    • Horizontal Motion: This motion is at a constant velocity (assuming no air resistance). There’s no horizontal force, so no horizontal acceleration.
    • Vertical Motion: This motion is under constant acceleration due to gravity ($g = 9.8 \text{ m/s}^2$ downwards). It’s essentially free fall in the vertical direction.
  • Gravity Acts Only Vertically: Gravity only pulls objects downwards. It does not affect horizontal motion.
  • Initial Velocity and Angle: The initial speed and launch angle determine the shape of the trajectory, how high it goes, and how far it travels.

Interactive: Projectile Launcher

Launch a projectile and observe its parabolic path, horizontal distance, and vertical height!

Projectile Motion Simulator A simulation showing a projectile launched at a given velocity and angle, tracing its parabolic path. Ground Launch Time: 0.0 s Range: 0.0 m Max Height: 0.0 m

Enter initial velocity and launch angle, then click "Launch" to simulate projectile motion!

Understanding the Trajectory

The parabolic shape of the trajectory is a direct result of the horizontal motion being constant and the vertical motion being constantly accelerated downwards.

  • At the peak of its trajectory: The vertical velocity of the projectile is momentarily zero, but its horizontal velocity remains constant.
  • Symmetry: For launches from level ground, the trajectory is symmetrical. The time to reach the peak height is half the total time of flight, and the horizontal distance covered to the peak is half the total range.

Interactive Match: Projectile Motion

Test your understanding of key terms related to projectile motion.

Click a term and then its matching meaning. Match all pairs to complete!

Audio Explanation

Prefer to listen? Here's a quick audio summary of projectile motion.

💡 Quick Concept Check:

A ball is launched horizontally from a cliff. What is its horizontal acceleration, and what is its vertical acceleration (ignoring air resistance)?

Click to Reveal Answer
Its horizontal acceleration is **zero** (constant horizontal velocity). Its vertical acceleration is **9.8 m/s² downwards** (due to gravity).

Ready to put your understanding of projectile motion into practice? Check out these related skills:

Practice Problems

Test your understanding and apply what you've learned with these problems.

```javascript // assets/js/motion-2d/projectile-motion-interactive-match.js // Specific data for the Projectile Motion Interactive Match. // This file now leverages the common interactive-match-base.js.

// Define the unique vocabulary data for this interactive const vocabDataProjectileMotion = [ { term: ‘Projectile Motion’, definition: ‘Motion of an object thrown into the air, subject only to gravity.’ }, { term: ‘Trajectory’, definition: ‘The curved path a projectile takes, which is always a parabola.’ }, { term: ‘Horizontal Motion’, definition: ‘Part of projectile motion with constant velocity and zero acceleration.’ }, { term: ‘Vertical Motion’, definition: ‘Part of projectile motion with constant acceleration due to gravity.’ }, { term: ‘Range’, definition: ‘The total horizontal distance traveled by a projectile from launch to landing.’ }, { term: ‘Time of Flight’, definition: ‘The total time a projectile spends in the air from launch to landing.’ } ];

// Define the unique element IDs for this interactive const interactiveOptionsProjectileMotion = { vocabData: vocabDataProjectileMotion, termsContainerId: ‘projectileMotionTerms’, definitionsContainerId: ‘projectileMotionDefinitions’, feedbackMessageId: ‘projectileMotionFeedback’, resetButtonId: ‘projectileMotionResetButton’ };

// Initialize the interactive match using the common base function // This function will be loaded AFTER interactive-match-base.js in the HTML. document.addEventListener(‘DOMContentLoaded’, () => { initInteractiveMatch(interactiveOptionsProjectileMotion); });

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