Parachute and lead–acid battery: what they have in common

1. Step 1. Parachute — is made of — Silk. The canopy is silk.
2. Step 2. Silk — is material for — Hot air balloon. The Montgolfier balloon was fabric lined with paper.
3. Step 3. Hot air balloon — uses — Archimedes’ principle. Warm air is lighter than cold — Archimedes’ principle in the atmosphere.
4. Step 4. Archimedes’ principle — is used in — Hydrometer. A hydrometer floats: the buoyant force depends on the liquid's density, so how deep it sinks shows the density.
5. Step 5. Hydrometer — is used in — Lead–acid battery. A car battery's charge is checked with a hydrometer by the density of its acid.

Open Evothings