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Hi. I got some question.These question is from 8th grade science.RememberAnswers must include science vocabulary terms(convection,radiaton, conduction...)

1.Explain what happens to an object when it is put into a refrigerator.

2.If you wanted to cool a large room with an air conditioner, would you get the best results by placing the unit near the floor or ceiling?

3. Explain how a hot air ballon works

4. Outdoors in winter, why does a piece of metal feel colder than a piece of wood?

5.Explain how heat is transferred from the stove to the water when you boil a pot of water. Then explain how the heat is tranferred in the water.

6. Starting with a piece of ice, explain what is required to change it into water and then water vapor. Remember to explain the phase changes in terms of heat.

7. What color is the outside( top) of a rainbow? What color is on the inside(bottom) of a rainbow? explain why the colors are in that order.

Answer 1

the basic premise is that heat rises, cool air stays closer to the flloor.

1. when an object goes into the frig, the heat from it raises the temp, which triggers the coolant to start and the fan to start too, cooling the air back down...and cooling the item.

2. heat rises......so cool the hot air and the room stays cooler, but this also uses more energy.

3. you fill the balloon with hot air, hot air rises (it does not hurt that the gas they use is lighter than air too)

4. metal conducts cold and heat, wood does not....it just burns.

5. the heat is conducted thru the metal (remember metal conducts cold/heat) you know the water is hot due to the bubbles (boiling) caused by the heat.

6 and 7....figure out yourself.......I have given you plenty of info!!!! (and I refuse to do all your homework for you)

Answer 2

1. The heat is absorbed from the object by the cold air in the refrigrerator. The heat is then removed from the air by the colder refrigerant coils and transferred outside the refirgerator. (the warm air blowing off the outside coils)

2. Ceiling, warm air rises, cold air is more dense and sinks. Drawing warm air in from the ceiling, then cooling it will cause it to sink and force warm air to the top. A cirrculation is created.

3. Its not the gas used. Air is heated by propane gas jets. Warm air is held in the balloon envelope. Warn air is less dense than cool air, thus the cooler dense air forces the balloon up into less dense air.

4. Metal conducts heat. Wood, because of its air pockets is an insulator and does not conduct heat well. Metal draws the heat out of your hand making it feel cold.

5. Heat from the stove coil transfers directly to the pot bottom. The pot is metal, a good heat conductor, and transferrs the heat to the bottom of the water column in the pot. Warmer water on the bottom (again less dense) pushes to less dense water at the top, forcing colder water to the bottom (more dense). A cirrculation is established thereby heating the entire water column.

6. Changing from a solid phase to liquid requires heat, 4 calories per gram, if I remember correctly. Ice will stay at 32°F until chandged into water. Then the liquid requires heat until it reaches its boiling point. Water requires additional heat to vaporize, sorry I don't remember the heat requirement. Water will stay at 212°F until vaporized.

7. ROY G BIV you figure it out or ask mom or dad. Red has the longest wavelength, violet the shortest. Violet bends more then red.

Read your book, I'm sure the answers are there somewhere. They were when I wa in school 40 years ago.

EDIT: Give a man a fish and he will eat for a day. Teach a man to fish and he will drink beer on the dock all day.

Answer 3

This site is not for homework. You are supposed to read the textbook and put the info into your brain, instead of getting it out of the brains of others. If you need help understanding a concept, I would help you.

Give a man a fire, and he will be warm for a day. Set a man on fire, and he is warm for the rest of his life.