Can hot water freeze faster than cold?
You Tube shows a video of university student Jim Sage on top of Mount Washington in heavy winter clothes boiling water on a small alcohol stove in the -34.8 F (-37.1 C) cold. Jim lifts the pot, and tosses boiling-hot water up then watches it snow down, like a blizzard, all around him. That’s fast freezing, but faster than cold water? It can happen, as Erasto B. Mpemba discovered in 1967 when he was a form-3 student (equivalent to North American 11th grade) making ice cream at Magamba Secondary School in Lushoto, a small town in Tanzania, Africa. Erasto asked his science teacher to explain why his hot milk froze faster than a friend’s cold milk. The teacher said, “You were confused; that cannot happen.” Erasto must have had some reservations about this reply because, over the next couple of years, he asked the same question of two more physics teachers, finally finding one with an open mind. Erasto’s day of discovery started like most school days. He woke up before dawn. Pulling on his
