Explain how heat is transferred between a hot and a cold object by conduction — for example, a warm foot on a cold floor.
http://en.wikipedia.org/wiki/Thermal_conduction
When heat is transferred between a hot and cold object by conduction, it happens through direct contact between the two objects. In the case of a warm foot on a cold floor, heat is transferred from the foot to the floor.
To understand this process, we need to delve into the scientific principles behind conduction. Heat is a form of energy that is transferred from a region of higher temperature to a region of lower temperature. When two objects of different temperatures come into contact, the particles in the hotter object gain kinetic energy (increased motion), while the particles in the colder object lose kinetic energy (decreased motion).
In the scenario of a warm foot on a cold floor, the foot is at a higher temperature than the floor. When the two surfaces touch, the particles in the foot start colliding with the particles in the floor. As a result, the foot's particles transfer some of their kinetic energy to the particles in the floor, making them vibrate faster. This increase in molecular movement in the floor raises its temperature.
The rate at which heat is conducted depends on various factors, including the nature of the materials involved and the temperature difference between them. Materials that are good conductors of heat, like metals, transfer heat more rapidly than poor conductors, such as air or some insulating materials.
To increase the rate of conduction between the foot and the floor, a larger area of contact can be established. This allows more particles to come into contact and transfer heat. For example, standing flat on the floor, rather than just the toes, would maximize the area of contact and promote greater heat transfer.
In summary, heat transfer by conduction occurs when two objects of different temperatures come into direct contact. In the case of a warm foot on a cold floor, heat is transferred from the foot to the floor through the collision of particles, causing an increase in temperature in the colder object (the floor).