Equal Masses. Unequal Answers.

Drop 100 g of aluminum at 90 °C into 100 g of water at 20 °C. Same mass, seventy degrees apart — so it settles at 55 °C, halfway. Every instinct says so. Every instinct is wrong, and the number that comes out instead tells you what temperature actually is, what heat actually is, and why they are not the same word.

8 STEPS · 6 QUICK CHECKS · q_Al + q_water = 0 · c_Al = 0.90, c_water = 4.18 J/(g·°C) · v1