Chapter 9 heat transfer and change phase

Would evaporation be a cooling process if the escaping molecules had the same average energy as those left behind?

No

On a cold day you wear both a black coat and a transparent plastic coat . Which should be worn on the outside for maximum warmth

Plastic coat on outside for maximum warmth

A farmer turns on propane burner in his barn on a cold morning and heats the air to 20c why does it still feel cold

The walks of the barn are still cold , he radiates. More energy to the walls than the walls radiate back at him and he feels chilly

Why will spraying fruit trees with water before a frost help to protect the fruit from freezing?

The water that is sprayed releases heat when it freezes. This heat raises the temperature of the tree and the air around it, and prevents the fruit from freezing. It acts as a thin layer of ice which acts as an insulating blanket against further loss of heat

You can bring water in a paper cup to a boil by placing it in a hot flame. Why doesn't the paper cup burn?

Water has high internal energy paper burns only at a temperature higher than boiling work

Why is whitewash sometimes applied to a glass of florists greenhouse.would you expect this practice to be more prevalent in winter or summer months

When it's desirable to reduce the radiant energy coming into a greenhouse, whitewash is applied to the glass simply to reflect much of incoming sunlight .energy reflected is energy not absorbed by the greenhouse

A piece of metal and a equal mass of wood are both removed from hot oven equal temp and dropped into blocks of ice . The metal has a lower specific heat capacity than wood , which would melt more ice before cooling to 0c

Wood, bc it has greater specific heat capacity means it will relies more energy in cooling

Wrap a fur coat around a thermometer, Will temperature rise

no fur coats insulate, which means wrapping the fur coat around a thermometer will protect it from getting warmer or colder

specific heat capacity of ice is about .5 c suppose it remains at the value all the way to absolute zero . Show that the heat required to change a1 gramice is 320 c

273*(.5)=140c from 0 c Ice to 0c water requires 80c total 320 140+80+320=540

A small block of ice at 0c is subjected to 10g of 100c steam and melts away completely.show that the mass of the block of ice can be no more than80grams

6400\80=80 grams of ice first find number of calories changing to 10 god 100 c steam will give in changing to 10 g of 0 c water 10 g of steam changing to 10g of boiling water at 100c relasese 5400 c 10g of 100c water cooling to 0c realrses 100 c , so 6400 c are available for melting

From the rules that a good absorber of radiation is a good radiator and a good reflector is a poor absorber , state a ruling the reflecting and radiating properties of a surface

A good reflector is a poor radiator of heat, and a poor reflector is a good radiator of heat

In terms of physics, why do restaurants serve baked potatoes wrapped in foil

Aluminum traps the heat

What does the high specific heat of water have to do with the convention currents in the air at seashore

Bc of high specific heat of water , sunshine warms much less than it warms land. If land and water were heated equally by the sun ,such convection currents and wind they produce wouldn't be

What is the explanation for feAther quilt being so warm on a cold winter night

Energy flows from higher to lower temperature, low internal energy feathers trap air it is an excellent insulator of heat

Wood is a better insulator than glass. Yet fiberglass is commonly used to insulate wooden buildings. Why?

Finberglass is a good insulator, many times better than glass, because of the air that is traped among its fibers and air is much better than wood at insulating.l

a number of bodies at different temperatures placed in a closed room share radiant energy and ultimately reach a common temperature. would this thermal equilibrium be possible if good absorbers were poor emitters and poor absorbers were good emitters, explain

Good absorbers were not also good emitters ,than thermal equilibrium would not be possible. If a good absorber only absorbed then its temperature would climb above that of poorer absorbers in the vincity , if poor absorbers weregoidemitersthrir their temp would fall below that of better absorbers

Turn an incandescent lamp on off quickly while standing near it , you feel heat but if u touch lamp it's not hot

Heat is from radiation

What is the purpose of the layer of copper or aluminum on the bottom of a piece of stainless steel cookware

Heats up faster to spread evenly

Of a good absorber of radiant energy were a poor emitter , how would it's temp compare with the temp of its surroundings

If a good absorber were not also a good emitter there would be a net absorption of radiant energy's day the temp would remain higher

In desert regions that are hot in the day and cold at night the walls of houses are often made of mud. Why is it important the walls be thick

It retains the warmth of the house by slowing the flow of internal energy from inside to outside