Heat transfer Steven barron
What is the role of "loose" electrons in heat conductors? • They carry energy from one part of the conductor to another.
Why does a piece of room-temperature metal feel cooler to the touch than paper, wood, or cloth? • The metal surface has a better ability to transfer heat from your fingers than the other materials, thus you sense that heat transmission as feeling cooler than the others.
Why are materials such as wood, fur, feathers, and even snow good insulators? • They all contain or can trap air which is a very good insulator/bad conductor of heat
What is meant by saying that cold is not a tangible thing? • Heat is created when molecules vibrate and move around. As the molecules move around heat energy is produced. As the molecules slow down heat is lost = cold. Cold is the lack of heat.
Why does the direction of coastal winds change from day to night? • In the daytime, the shore warms more easily than the water. Air over the shore rises, and cooler air from above the water takes its place. The result is a sea breeze. At night the process reverses as the shore cools off more quickly than the water -- the warmer air is now over the sea.
How does the temperature of a gas change when it is compressed? Expands? • Pv=nrt. The temperature is directly related to pressure. If compressed, it gets hotter, if it expands, it gets colder
What is radiant energy? • is the energy of electromagnetic waves
Why does a good absorber of radiant energy appear black? • It is just that matt black things are good absorbers (and emitters) of radiant energy.
Why do eye pupils appear black? • they absorb light therefore not releasing any. but some light does manage to escape. but the black pigment in the pupil makes it appear dead black.
Is a good absorber of radiation a good emitter or a poor emitter? • It is a good emitter, as you can not have a good absorber, which isnt a good emitter. Dark, matt surfaces are good emitters and absorbers e.g. a saucepan.
Does Newton's LAW OF COOLING apply to warming as well as to cooling? • yes