How does sound travel? As a push passed from molecule to molecule, not as moving air: in air at 20 °C it travels at 343 m/s.
In iron it runs at 5,130 m/s, about 15 times faster, so one clang on a long iron bar arrives twice. Lead is denser than iron, yet sound in lead is just 1,322 m/s: stiffness speeds sound up, density slows it down.
Full explanation (about 11 minutes):
Sources:
– HyperPhysics, Speed of Sound table:
– HyperPhysics, Speed of Sound in Other Media:
– HyperPhysics, Longitudinal Waves:
– HyperPhysics, Density table:
Sources checked 15 Oct 2026. Speeds in air and water are at 20 °C; the iron and lead speeds are from one textbook table (HyperPhysics). The “about 15 times” figure is our calculation (5,130 / 343 = 14.96).
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