A wonderful site that contains physics simulators, video tutorials, and numerous resources to help any student or teacher.
From the ‘About’ section:
“The Physics Classroom is an online, free to use physics website developed primarily for beginning physics students and their teachers. The website features a variety of sections intended to support both teachers and students in the tasks of learning and teaching physics.
The Physics Classroom Tutorial is among the most popular sections of the website. The Tutorial covers basic physics topics using informative graphics and an easy-to-understand language. Each unit is divided into lessons and sub-lessons. A lesson resembles the type and extent of coverage typically given to that topic in class. The sub-lessons are accompanied by Check Your Understanding sections, providing an opportunity to assess one’s understanding of the lesson material. The Tutorial, when combined with other sections at this site, provides a student of physics a great opportunity to learn and to test their physics understanding.”