I spent a lot of my childhood with hotwheels, whether it be putting insane tracks together or just watching the cars fly around the track. Hotwheels are best described as miniature cars that can be sent around tracks at ridiculous speeds to do crazy things. Some of the stunts my cars did were jumping tracks, going through King Kong's mouth, and doing loops around other sections of track.
The cars are usually launched by two spinning foam wheels that rotate in opposing directions with a small gap in between for the car. This pushes the car really quickly forward, launching it onto the track. Part of the difficulty with setting up a Hotwheels track was getting the "boosters" in the right spot so that the car would succeed in all the stunts and wouldn't get stuck anywhere. Because the cars are small and light, they can be easily launched really fast and can do crazy things. I haven't kept up to date with the new types of stunts and other new stuff, but all of the stunts my cars did blew my mind, because I always believed that if the cars were scaled up to real life, it would work the same way. But physics has taught me otherwhise, because it would be insanely difficult to send a 4 ton car around a huge loop, let alone creating a structurally sound loop to begin with. Hot wheels cars are much lighter for their size than full size cars are, meaning that the whole situation wouldn't work at all. Hotwheels has made some videos of minor attempts to recreate some stunts, and they have all been fairly successful. The way they accomplished this was by scaling down the stunts, and using heavily modified cars. Without this, the cars would have absolutely not completed the loop, and fallen on their roofs. A lot of car or bike stunts involve jumping, or doing a loop. Hotwheels cars are a good demonstration for young kids how friction and gravity affect motion.