12 Physics-based animations
This chapter covers
- Understanding how real-world physics improves user experience in animations
- Applying velocity and acceleration equations in JavaScript
- Creating gravity and bouncing effects with mathematical precision
- Implementing spring and friction-based animations using physics formulas
When you watch a leaf fall from a tree, a ball bounce on the ground, or a pendulum swing back and forth, your brain instinctively recognizes these movements as natural and "correct" in some hard-to-define way. That's because these motions follow the fundamental laws of physics that govern everything in our world. When you bring these same principles into your web animations, something magical happens: your interfaces start to feel more intuitive, more responsive, and more delightful to use.
The secret isn't just making things move, it's making them move the way users expect based on their lifetime of experience with the physical world. A modal that slides into view with constant velocity feels robotic and artificial. But a modal that starts fast and gradually slows down as it settles into place? That feels natural, because that's how objects behave when they're subject to friction and momentum in the real world.