# Densities of materials in kg/m^3.
# FIXME: friction belongs per pair of materials; genesis-world resolves `max(mu_a, mu_b)`
# until it supports pairs.
# --- polymers ---
abs_plastic:
  rho: 1040.0 # ABS (MatWeb, injection-moulding grades)
polypropylene:
  rho: 920.0 # PP homopolymer (MatWeb)
hdpe:
  rho: 950.0 # High-density polyethylene (MatWeb)
acrylic_pmma:
  rho: 1180.0 # Cast PMMA (MatWeb)
nylon:
  rho: 1140.0 # Nylon 6/6, unfilled (MatWeb)
silicone_rubber:
  rho: 1200.0 # Unfilled silicone elastomer (MatWeb)
# --- ceramics and glass ---
stoneware_ceramic:
  rho: 2300.0 # Glazed stoneware (Ceramic Industry handbook)
porcelain:
  rho: 2400.0 # Vitrified porcelain (Ceramic Industry handbook)
glass:
  rho: 2500.0 # Soda-lime glass (Corning)
# --- metals ---
aluminium:
  rho: 2700.0 # Al 6061-T6 (MatWeb)
steel:
  rho: 7850.0 # Low-carbon steel (MatWeb)
stainless_steel:
  rho: 7900.0 # AISI 304 (MatWeb)
# --- wood and paper ---
pine:
  rho: 500.0 # Softwood at 12% moisture (Wood Handbook Tab. 4-3)
oak:
  rho: 750.0 # Red oak at 12% moisture (Wood Handbook Tab. 4-3)
plywood:
  rho: 600.0 # Softwood plywood (APA Engineered Wood Handbook)
cardboard:
  rho: 700.0 # Solid-fibre paperboard (TAPPI)
paper:
  rho: 800.0 # Uncoated office paper (TAPPI)
# --- moulded replicas ---
# Bulk density over the solid collision volume. A replica is a hollow shell, so this sits far below
# the polymer it is moulded from.
plastic_produce:
  rho: 100.0 # Geometric mean of the seven produce twins weighed in #3638, which span 50-160