Question

In which of these situations is convection most likely the main form of heat transfer?
Warm air from a heater on the first floor of a house moves to the upper floors.
The sides of a metal pan become hot when the pan is placed on a stove burner.
A person gets a sunburn from lying on the beach too long.
An ice cube melts when a person holds it in his hand.

Answer 1

Warm air from a heater on the first floor moving to the upper floors — this is convection (bulk movement of a fluid, here air, carrying heat).

Brief reasons the others are not primarily convection:
- Metal pan sides on a burner: conduction through the metal.
- Sunburn on the beach: radiation from the Sun.
- Ice cube melting in a hand: conduction from the warm hand to the ice.