Explain how heat is transferred between a hot and a cold object by conduction — for example, a warm foot on a cold floor.
Conduction is the transfer of heat from a hot object to a cold object through direct physical contact. In the case of a warm foot on a cold floor, heat is transferred through conduction from the foot to the floor.
When your warm foot touches the cold floor, the molecules in your foot increase their kinetic energy due to the higher temperature. These energetic molecules collide with the molecules in the floor, which have lower kinetic energy. Through these collisions, the energy is transferred from the molecules in your foot to the molecules in the floor.
To understand this further, it is helpful to visualize the atoms or molecules as tiny particles. When the particles in your foot make contact with the floor, they begin to vibrate vigorously. This vibration spreads from one molecule to another in the floor, transferring energy in the process. As a result, the temperature of the molecules in the floor increases while the temperature of the molecules in your foot decreases.
The rate of heat conduction depends on several factors, including the temperature difference between the objects, the thermal conductivity of the materials, and the surface area of contact. Materials with high thermal conductivity, such as metals, generally conduct heat more efficiently than materials with lower conductivity, such as wood or carpet.
In the example of your warm foot on a cold floor, the heat conduction will continue until both objects reach thermal equilibrium, which means they reach the same temperature. This process occurs until the heat from your foot spreads throughout the floor, causing the floor to warm up and your foot to cool down.