![](https://image.tmdb.org/t/p/w342/XOoVyYtPqoUsHMVqMvkQACJPIT.jpg)
All machines in the world can be traced to just two: the inclined plane and the lever. Even the wheel is just a circular lever whose fulcrum has become an axle. The screw? It's just a spiraling inclined plane.
![](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
Other episodes for this season
![The Inclined Plane](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![The Lever](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Mechanical Advantage and Friction](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![The Screw and the Wheel](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![The Pulley](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Molecules in Solids](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Molecules in Liquids](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Evaporation and Condensation](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Expansion and Contraction](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Measuring Temperature](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Temperature vs. Heat](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Atoms](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Electrons](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Conduction](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Volume and Density](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Buoyancy](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Convection](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Heat as Energy](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![Radiation Waves](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
![The Radiation Spectrum](https://image.tmdb.org/t/p/w300/kpBwfhW4mqhPETcJ3u8X5HXCxhX.jpg)
All machines in the world can be traced to just two: the inclined plane and the lever. Even the wheel is just a circular lever whose fulcrum has become an axle. The screw? It's just a spiraling inclined plane.