Scalds and Spills: Contact Times at Kitchen Temperatures, and the Fill Fraction That Keeps a Carried Pot from Spilling

Two everyday kitchen hazards are treated with two stated models. For thermal injury, adopted time-temperature pairs for a second-degree burn in adult skin (300 s at 50 C, 30 s at 55 C, 5 s at 60 C, 2 s at 65 C, 1 s at 70 C) imply that tea water at 85 C, soup at 75 C, and frying oil at 180 C each reach that injury in at most 1.0 s - no more than a stated human response time of 1.0 s, so the margin for withdrawing is zero or negative; soup cooled to 60 C restores a margin of 4.0 s. For carrying, a cylindrical pot walked at a step frequency of 1.8 Hz with a horizontal acceleration amplitude of 0.20 g spills unless its freeboard exceeds a dynamically amplified wall rise. The resulting maximum fill fractions are not monotone in pot size: 67.7 percent for a 16 cm pot, only 33.3 percent for a 20 cm pot and 33.5 percent for a 24 cm pot, 42.4 percent for a 28 cm pot, and 53.1 percent for a 32 cm pot. The mid-sized pots are the restrictive ones because their sloshing natural frequencies, 1.82 Hz and 1.67 Hz at the limiting fill, lie closest to the walking frequency and amplify the motion most. A pot carried at 90 percent fill spills in every case computed. SIMULATED, NOT MEASURED.