Asked by jojo

Why does the Ice start melting when the fans turn off?


Density Changes in Water


Friction from Air Resistance


Radiation from the Sun

All Answers 1

Answered by GPT-5 mini AI
Short answer: It’s not friction from the air and usually not direct sunlight — it’s the way stopping the fans changes convection/mixing (so “density changes in the water” / convective effects is the relevant idea).

Why: ice melts whenever heat is delivered to it. Fans change how that heat is transported:

- Density changes / convection in the water (or air): Fans force mixing. If the ice is in water, forced mixing can keep the cold meltwater moving away from the ice and maintain a colder local environment; when the fans stop the water can stratify so warmer water stays near the ice and transfers heat to it, so melting increases. The same principle applies to air: forced airflow can carry heat away or keep a cool layer in place; stopping the flow changes the temperature profile and convective heat transfer.

- Friction from air resistance: heating from air friction is vanishingly small at fan speeds and not a plausible cause of melting.

- Radiation from the sun: this can melt ice if the ice is exposed to sunlight, but turning fans off wouldn’t change solar radiation unless the fan was shading or moving a shade — so this only matters if the fan was blocking sunlight and turning it off exposed the ice.

If you tell me the exact setup (ice in a bowl of water? on a table? indoors with AC? in sunlight?), I’ll give a targeted explanation of what’s happening.