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Physics uses simple yet elegant math to describe complex phenomena, from galaxies to biological systems. It's about understanding and predicting the universe's complexity based on simple ideas.

Learn physics using videos, articles, and NGSS-aligned practice exercises. Explore the fundamentals of motion and forces, non-contact interactions, energy, and waves.

Let's think about what physics is and what topics are covered in an introductory physics course.

We can't "see" frequency in a stationary diagram, since frequency involves change over time. But, we can visualize frequency with a simple example. Imagine you're creating water waves by dripping …

Aug 14, 2025 · Hands-on activities prompt students to explore and investigate science in action with real-world questions and simple materials. Our growing collection of middle and high school activities …

Scalars and vectors are two kinds of quantities that are used in physics and math. Scalars are quantities that only have magnitude (or size), while vectors have both magnitude and direction. Explore some …

Weight W is just another word for the force of gravity F g . Weight is a force that acts at all times on all objects near Earth. The Earth pulls on all objects with a force of gravity downward toward the center …

The physics archive contains legacy physics content, and is not being updated with new content. For our most up-to-date, mastery-enabled courses, check out Middle School Physics, High School Physics, …

Practice Simple harmonic motion: Finding speed, velocity, and displacement from graphs Practice