Nuclear density
The average density of matter within an atomic nucleus, approximately ρ ≈ 2.3 × 10¹⁷ kg/m³. Nuclear density is essentially constant across nuclei of different sizes: density = (total nucleon mass) / (nuclear volume).
Formula
ρ ≈ 1.67×10⁻²⁷ / (4/3 π r₀³) ≈ 2.3×10¹⁷ kg/m³
Real World
A neutron star — essentially a giant atomic nucleus — packs roughly 1.4 solar masses into a sphere ~10 km across, with density matching nuclear density, confirmed by gravitational wave observations from LIGO's detection of colliding neutron stars in 2017.
Exam Focus
Show the A cancels in the density derivation to prove density is independent of mass number — examiners expect this algebraic step explicitly shown.
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