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CONDUCTION

WENCH NISSI OCCIDA JIMLOU TRONO

OBJECTIVES

By the end of this lesson, you will be able to: Calculate Thermal conductivity Observe Conduction of Heat Collisions

3. Study Thermal Conductivities of common substances

In the process of conduction of heat, the heat flows within and through the object itself. In the solids, conduction is carried out by the combination of collisions and vibration of molecules. In gases and liquids, conduction occurs due to collisions of molecules during their irregular motion..

EXAMPLE OF CONDUCTION OF HEAT

TRANSFER

1.Utensils used to handle charcoal or other very hot substances. Keep

in mind that the extension is long so that the heat transfer is slower.

2. The ice, when put in a cup of boiling water, melts completely.

3. When you bring water to a boil, the gas stove flame transmits the

heat to the pot, and from one moment to the next the water is already

heated.

4. The heat that comes from a kitchen utensil when you leave it on a

container and turn over it a soup that is practically burning.

The rate at which energy is conducted as the heat between two bodies depends on the temperature difference between the two bodies which are in contact with each other.The heat automatically flows from a hotter body to a colder body.

For example, heat flows from the hot plate of a stove to the bottom of a saucepan in contact with it

The heat flux thus depends on the temperature difference Δ Τ = Τ hot − Tcold. Conversely, if the temperatures are the same, the net heat transfer rate falls to zero, and equilibrium is achieved. Owing to the fact that the number of collisions increases with increasing area, heat conduction depends on the cross-sectional area.

Lastly, the heat transfer rate depends on the material properties described by the coefficient of thermal conductivity.

Q over t is the rate of heat transfer - the amount of heat transferred per second, measured in Joules per second, or Watts k is the thermal conductivity of the material T1 is the temperature of one object, and T is the temperature of the other. d is the thickness of the material we're interested in. whereas;

Equation

TRY AND

LEARN

EXAMPLE # A Styrofoam ice box has a total area of 0.950 m2 and walls with an average thickness of 2.50 cm. The box contains ice, water, and canned beverages at 0ºC. The inside of the box is kept cold by melting ice. How much ice melts in one day if the ice box is kept in the trunk of a car at 35.0ºC?

SOLUTION GIVEN: A= 0.950 m2; d=2.50 cm=0.0250 m; T1=0∘C; T2=35.0∘C; t=1 day=24hours=86,400 s. REQUIRED: m(ice)=? Q=?