Egyptian pyramid and sonar: what they have in common

1. Step 1. Egyptian pyramid — uses — Inclined plane. According to a common hypothesis, the blocks were raised on ramps.
2. Step 2. Inclined plane — evolved into — Screw. A screw is an inclined plane wrapped around a cylinder.
3. Step 3. Screw — is used in — Propeller. A propeller “screws” itself into the water, like an Archimedes’ screw.
4. Step 4. Propeller — is part of — Submarine. A propeller.
5. Step 5. Submarine — has part — Sonar. Underwater acoustics.

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