The three methods of heat transfer in a fireplace are conduction, convection, and radiation.
Most of the heat goes into the room because of radiation.
At a slower rate, heat transfer occurs through the room.
Through cold air entering the room around windows and hot air leaving the room by rising up the chimney, heat transfer occurs.
In the three following modules, we examine the methods in some detail.
As you hold a hot cup of coffee, heat transfers into your hands.
The barista makes hot cocoa by steaming cold milk.
Coffee can be reheated in a microwave oven.
In the winter and the summer, insulation is used to limit the heat from the inside to the outside.
As you walk barefoot across the living room carpet in your cold house, your feet feel cold as you step onto the kitchen tile floor.
The carpet and tile floor are both at the same temperature.
The difference in temperature between the tiles and the carpet is explained by the different rates of heat transfer: the heat loss during the same time interval is greater for skin in contact with the tiles than with the carpet, so the temperature drop is greater on the tiles.
Some materials are able to produce more thermal energy than others.
Good conductors of electricity, such as copper, aluminum, gold, and silver, are also good heat conductors.
The hotter the body, the higher the molecule's energy is.
The temperature difference affects the heat flux.
You will get a worse burn from boiling water than from hot tap water.
The net heat transfer rate falls to zero if the temperatures are the same.
The number of collisions increases as the cross-sectional area increases.
If you touch a wall with your hand, it will cool quicker than if you touch it with your finger.
Molecules in two bodies have different averages.
Energy is transferred from high-temperature regions to low-temperature regions when there is a collision at the contact surface.
The molecule in the lower temperature region has low energy before it collides with the surface, but it has more energy after it hits it.
A molecule in the higher temperature region has high energy before it collides with the contact surface, but its energy decreases after it collides with the surface.
The thickness of the material transfers heat.
There is a slab of material with different temperatures on either side.
If that is greater, then the heat is transferred from left to right.
The transfer of heat from the left side to the right side is accomplished by a series of collisions.
The thicker the material, the longer it takes to transfer heat.
This model explains why thick clothing is warmer than thin clothing in the winter.
The rectangular bar is a representation of heat conduction through any material.
The material's temperature is on the left and right.
The surface area, temperature difference, and substance's conductivity are all related to the rate of heat transfer.
The thickness is related to the rate of heat transfer.
The heat transfer rate depends on the material properties.
Experiments confirm that all four factors are included in a simple equation.
The values of thermal conductivity are given in Table 14.
An average thickness of 2.50 cm is the average thickness of a Styrofoam ice box.
melting ice keeps the inside of the box cold.
The question is about heat for a phase change and the transfer of heat.
We must find the net heat transferred to find the amount of ice melted.
The rate of heat transfer can be calculated with the help of time.
The knowns should be identified.
The unknowns should be identified.
The mass of ice needs to be solved.
The net heat that is transferred to melt the ice will need to be solved.
Determine which equations to use.
The result of 3.44 kg, or about 7.6 lbs, seems to be right based on experience.
A bag of ice can weigh up to 10 lbs per day.
Extra ice is required if you add warm food or beverages.
Styrofoam is a poor conductor and is a good insulator.
Wool, fiberglass, and goose-down feathers are good insulators.
These all incorporate small pockets of air, taking advantage of the poor thermal conductivity of air.
A combination of material and thickness can be manipulated to create good insulators.
A good insulator will have a large ratio.
The rate of heat transfer is proportional to that.
A couple of representative values are 11 for 3.5-in-thick fiberglass batts and 19 for 6.5-in-thick fiberglass batts.
Walls and ceilings are usually insulated with 3.5-in batts.
In cold climates, thicker batts can be used.
The fiberglass batt is used for insulation of walls and ceilings to prevent heat transfer between the inside of the building and the outside environment.
The best thermal conductors are silver, copper, gold, and aluminum, and they are related to the density of free electrons in them.
Good conductors are used to make cooking utensils.
The water is boiling in the pan on the stove.
The sauce pan has a thick bottom that is 14.0 cm in diameter.
The water is being evaporated at a rate of 1.00 g/s.
Conduction through the aluminum is the primary method of heat transfer here, and so we use the equation for the rate of heat transfer and solve for the temperature difference.