Founded in 2002 by Nobel Laureate Carl Wieman, the PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. PhET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery.

Explore physics 

Forces, motion and energy - from the BBC

Sir Isaac Newton’s Laws of motion describe how forces cause changes to the motion of an object, how gravity gives weight to mass; how forces cause acceleration and how forces work in collisions.

• PhysicsCentral - learn how your world works

The audio recordings of the Feynman Lectures on Physics (1961-64) are now publicly available.