Shoe upper and rocket: what they have in common

1. Step 1. Shoe upper — is part of — Trainers. A mesh upper.
2. Step 2. Trainers — is made of — Vulcanized rubber. The sole.
3. Step 3. Vulcanized rubber — is material for — Weather balloon. The envelope is rubber or latex.
4. Step 4. Weather balloon — is made of — Hydrogen. Filled with hydrogen or helium.
5. Step 5. Hydrogen — is used in — Liquid-propellant rocket engine. Hydrogen is an efficient fuel.
6. Step 6. Liquid-propellant rocket engine — evolved from — Rocket. Goddard switched to liquid fuel.

Open Evothings