Hourglass wooden frame and liquid-propellant rocket engine: what they have in common

1. Step 1. Hourglass wooden frame — is part of — Hourglass. A protective frame.
2. Step 2. Hourglass — uses — Gravity flow. Sand pours through under gravity.
3. Step 3. Gravity flow — is used in — Water filter. Water seeps through by gravity.
4. Step 4. Water filter — is made of — Silica (sand). Slow filters are layers of sand and gravel.
5. Step 5. Silica (sand) — is material for — Space Shuttle. The heat-shield tiles are silica fibre.
6. Step 6. Space Shuttle — has part — Liquid-propellant rocket engine. Hydrogen-fuelled main engines.

Open Evothings