When a warm hand is immersed in water at 70°F (21°C), heat is transferred from the hand to the water through which mechanism?

When a warm hand is immersed in water at 70°F (21°C), heat is transferred from the hand to the water through which mechanism?

• A. Conduction
• B. Convection
• C. Radiation
• D. Evaporation

Answer: (A)

Conduction is the mechanism at work here because heat moves through direct contact from the warmer hand into the cooler water. The skin and the water touch each other, and energy transfers from the hand’s molecules to the adjacent water molecules, warming the water and cooling the hand until temperatures approach equilibrium. Radiation would involve energy transfer without contact, evaporation would require the water to change phase, and convection refers to moving fluid carrying heat, which can enhance transfer but does not describe the initial boundary process.

Conduction is the mechanism at work here because heat moves through direct contact from the warmer hand into the cooler water. The skin and the water touch each other, and energy transfers from the hand’s molecules to the adjacent water molecules, warming the water and cooling the hand until temperatures approach equilibrium. Radiation would involve energy transfer without contact, evaporation would require the water to change phase, and convection refers to moving fluid carrying heat, which can enhance transfer but does not describe the initial boundary process.