Consider 2 differen… - QuestionCove
OpenStudy (anonymous):

Consider 2 different covered cups containing the same amount of hot water, initially at the same temperature. Which of the cups will cool down at a faster rate? Cup A (Covered Styrofoam Cup) has 100 g of water, and it is 55 ℃ Cup B (Covered Shiny Metal Cup) has 100 g of water, and it is 55 ℃ 1. Not enough information is given. 2. Cup A will cool faster than cup B. 3. Both cups will cool at the same rate. 4. Cup B will cool faster than cup A.

3 years ago
OpenStudy (rajat97):

i think option 2 is correct as, if we cover a cup with a shiny metal cup, the shiny surface will reflect the heat that is gonna be lost

3 years ago
OpenStudy (anonymous):

That's what I thought too, but I wasn't sure.

3 years ago
OpenStudy (rajat97):

i think what you(and me) thought was right!

3 years ago
OpenStudy (anonymous):

So, Cup A (Covered Styrofoam Cup) will cool faster than cup B (Covered Shiny Metal Cup), right?

3 years ago
OpenStudy (anonymous):

No, it is not option 2!

3 years ago
OpenStudy (anonymous):

Wouldn't both cups cool at the same rate, option 3.

3 years ago
OpenStudy (anonymous):

?

3 years ago
OpenStudy (anonymous):

Hey, are you there?

3 years ago
OpenStudy (anonymous):

Wouldn't both cups cool at the same rate, which is option 3?

3 years ago
OpenStudy (anonymous):

Help!

3 years ago
OpenStudy (anonymous):

Someone there?

3 years ago
OpenStudy (anonymous):

what is difference between metal and styrofoam?

3 years ago
OpenStudy (fifciol):

metals have the greater ability to conduct heat than styrofoam,so metals would maintain the heat less then styrofoam. But as rajat97 said metal can reflect the heat while styrofoam can't. So metal is gonna lost heat due to heat conduct ability relative to styrofoam but is gonna keep heat longer due to reflection of heat waves. You cannot tell now whith information given which material would cool faster. I think it's A

3 years ago
OpenStudy (anonymous):

I also feel not enough information is given. The metal cover will conduct the heat more than the styofoam but as Fifciol said, it would also reflect more heat than the foam.

3 years ago
OpenStudy (anonymous):

Here's another question: The same two cups, under the same conditions, but this time Cup A is covered with shiny metal cup, and cup B covered with dull black cup, which of the cups will cool down at a faster rate?

3 years ago
OpenStudy (anonymous):

same mass, same temperature.

3 years ago
OpenStudy (anonymous):

Here's another question: The same two cups, under the same conditions (same mass, same temperature), but this time Cup A is covered with shiny metal cup, and cup B covered with dull black cup, which of the cups will cool down at a faster rate?

3 years ago
OpenStudy (anonymous):

It will probably be the dull black cup. If you look on the inside of a thermo flask you will see a reflective lining on the inside. This is to keep the heat in. A black dull cover will absorb heat radiation, have a look at black body radiation on wiki

3 years ago
OpenStudy (anonymous):

So, Cup B (covered will dull black cup) with cool down faster than Cup A (Shiny Metal Cup)?

3 years ago
OpenStudy (anonymous):

I think that's what the question is getting at, maybe someone else will see it a different way.

3 years ago
OpenStudy (anonymous):

Yeah, you were right!

3 years ago
OpenStudy (anonymous):

3 years ago
OpenStudy (anonymous):

I also feel not enough information is given, but I'm scared to enter the answer; I get negative points if the answer is wrong!

3 years ago
OpenStudy (anonymous):

Excellent! I'm not sure myself about the first question, it's either conduction of the metal emitting more heat radiation or the metal reflecting more heat thus cool down at a faster rate. I couldn't give a reliable answer, maybe someone else might have a little more insight

3 years ago
OpenStudy (anonymous):

Thank you so much - I really appreciate it! I hope someone else can help with that question.

3 years ago
OpenStudy (rajat97):

good absorbers are good reflectors i think this concept is used in both the questions

3 years ago
OpenStudy (rajat97):

oh i' sorry good absorbers are good emmitors

3 years ago
OpenStudy (anonymous):

So, what would be the answer?

3 years ago
OpenStudy (rajat97):

for question 1, i'm not sure as i think that optoion 2 is correct for the second question , i have a logic look dull black things are good absorbers and good absorbers are good emmitors so the black cup will emmit its heat faster and cool down faster hope this helps you 'll get back and help you:)

3 years ago
OpenStudy (vincent-lyon.fr):

The cups are not covered by styrofoam or metal, but as I understand it are MADE of styrofoam or metal. The metal cup will cool much faster as metal is a much better heat conductor than styrofoam.

3 years ago
OpenStudy (anonymous):

So, Cup B (Covered Shiny Metal Cup) will cool faster than cup A (Covered Styrofoam Cup), right?

3 years ago
OpenStudy (anonymous):

Yeah, you were right! Thank you so much for all the help! :-)

3 years ago