Which of these materials will heat up faster and why?

In summary: The thermal conductivity of different materials affects how quickly heat is transferred from one place to another. In summary, the cup with the highest water temperature will be the one with the black back side, which absorbs the most sunlight.
  • #1
mrchopsy
5
0
Hello,

I am doing a high school EEI to investigate the impact that the material of a cup has on the temperature of water inside the cup when left outside in the sun.
The cups I am using are:

Glass
Steel
Plastic
Paper

Theoretically, if I poured the same amount of water into each of the cups (assuming the size and shape of the cups were identical) and left them out in the hot sun (approx 30 degrees Celcius) for an hour, which of the cups will have the hottest water temperature and why?

Thank you!
p.s. this is my first post so I'm not sure if I've posted this in the right forum
 
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  • #2
Welcome to the PF. :smile:

I've moved your thread to the Homework Help forums. All schoolwork-type questions go here in the HH forums.

We require that you show us your work so far before we can offer any tutorial help. What material properties will influence the answers? What do you think the answers are, and why?
 
  • #3
Also, you did not specify the color of the cups. Why would that matter? :smile:
 
  • #4
Welcome to PF.

Do you know the colors of the cups? A black one will absorb sunlight faster than a white one, sometimes a transparent one faster still.

For example, camp showers like the one below are transparent on the front and black on the back to heat water as fast as possible.

-shower-bags-solar-outdoor-portable-thickening-water-bag-sun-shower-bags-20L-bathing-bag-Camping.jpg
 

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  • #5
anorlunda said:
Welcome to PF.

Do you know the colors of the cups? A black one will absorb sunlight faster than a white one, sometimes a transparent one faster still.

For example, camp showers like the one below are transparent on the front and black on the back to heat water as fast as possible.

View attachment 223496
20 litres will run out half way through rinsing off the soap. I've been there!
 
  • #6
mrchopsy said:
Hello,

I am doing a high school EEI to investigate the impact that the material of a cup has on the temperature of water inside the cup when left outside in the sun.
The cups I am using are:

Glass
Steel
Plastic
Paper

Theoretically, if I poured the same amount of water into each of the cups (assuming the size and shape of the cups were identical) and left them out in the hot sun (approx 30 degrees Celcius) for an hour, which of the cups will have the hottest water temperature and why?

Thank you!
p.s. this is my first post so I'm not sure if I've posted this in the right forum
There are three main methods of heat transfer - conduction, convection, and radiation. If you don't already know the difference between them, you can look them up to get an idea of how they work. Then think about which ones will be applicable to your experiment, and why. Are there any environmental factors that might also be at work?

Good luck!
 
  • #7
mrchopsy said:
when left outside in the sun.
How long for? Open or covered? The thread title refers to the rate of heating, but in your post you wrote:
mrchopsy said:
temperature of water inside the cup
So which is it, the rate of increase or the temperature reached?
mrchopsy said:
the hot sun (approx 30 degrees Celcius)
That sounds like the ambient temperature. A suitably designed hotbox (a car for instance) can get a lot hotter.
anorlunda said:
sometimes a transparent one faster still.
Not if transparent both sides, surely? Something has to absorb the rays.
 
  • #8
haruspex said:
Something has to absorb the rays.
Yes. The black back face of the container. (A misunderstanding, I think) The transparent front bit will absorb and radiate less (none) and the backing can transfer more heat to the water and only a little to the surroundings. An outer insulating sheet behind the back would help further.
 
  • #9
sophiecentaur said:
20 litres will run out half way through rinsing off the soap. I've been there!
What do you expect? Silverbacks have a lot of fur! :smile:
 
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Likes sophiecentaur and anorlunda
  • #10
Hello, thank you for the replys and apologies for my late reply.

I believe the thermal conductivity of the materials, as well as the colour of the materials will be the main factors that influence how quickly the water heats up inside of the cups.

In my hypothesis I stated that steel will heat up the quickest because it has the highest thermal conductivity, k.

I actually did the test, and it turned out that the water inside the glass (transparent) cup heated up fastest.

Now my question is, why would this be the case? The thermal conductivity of steel is approximately 30 to 40 times greater than that of glass. I don't expect direct answers, but it would be great if someone could help to steer me in the right direction, since I have tried to discover why through research, but have not been able to find anything to help.

Thank you
 
  • #11
You're learning some good physics here. Apparently, it is the sunlight absorbed by the object that is more important than thermal conductivity. What are the factors that affect sunlight absorption/reflection/transparency?

Completely transparent things neither absorb nor reflect, but what about water? Is the ocean warmed by sunlight?
 
  • #12
anorlunda said:
You're learning some good physics here. Apparently, it is the sunlight absorbed by the object that is more important than thermal conductivity. What are the factors that affect sunlight absorption/reflection/transparency?

Completely transparent things neither absorb nor reflect, but what about water? Is the ocean warmed by sunlight?

But if the glass is transparent, meaning that it doesn't absorb or reflect, then why would the water in the glass be heating up faster? And yes, the ocean is warmed by sunlight isn't it? hence why it evaporates, but I'm sure some of the sunlight is also reflected rather than absorbed.
 
  • #13
I'm so confused about the results and am not able to find much help online
 
  • #14
ahhh, the glass cup was a lot thicker than the others, could this possibly be the reason why the glass cup heated up the fastest?
 
  • #15
As @anorlunda pointed out, the color of the cup is relevant as a control parameter. What if you took three identical paper cups, painted one black, one white and wrapped tin foil around the third? You can repeat with the other materials and study the effect that the color has for a given material and the effect that material has for a given color.
 
  • #16
mrchopsy said:
But if the glass is transparent, meaning that it doesn't absorb or reflect, then why would the water in the glass be heating up faster? And yes, the ocean is warmed by sunlight isn't it?

I'm surprised you don't see the connection. Why shouldn't the sunlight heat the water in the glass like it heats the ocean? The opaque cup materials kept the water in the shade, and as you know it feels cooler in the shade.

This curve may help explain. IR stands for infrared. Most heat in sunlight is in the infrared part of the spectrum.
[URL='http://By Kebes at English Wikipedia said:
1200px-Absorption_spectrum_of_liquid_water.png

Edit: Strange, you must click on that figure to see it full size.
 

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  • #17
mrchopsy said:
steel will heat up the quickest because it has the highest thermal conductivity, k.
But steel is also quite reflective.
mrchopsy said:
glass (transparent) cup heated up fastest.
Sunlight is not just visible light. The infrared will be important too.
Water is opaque to IR. Some glasses block more IR than others; maybe the glass you used is fairly transparent to it.
 

Related to Which of these materials will heat up faster and why?

What are the different materials in question?

The materials in question are typically metals such as copper, aluminum, iron, and steel. These materials have different properties that affect how they heat up.

What factors affect the rate at which materials heat up?

The rate at which materials heat up is affected by several factors, including the material's specific heat capacity, thermal conductivity, density, and surface area.

Which material will heat up faster?

The material with the lowest specific heat capacity and highest thermal conductivity will heat up the fastest. This is because it requires less energy to increase the temperature of a material with a lower specific heat capacity, and materials with higher thermal conductivity transfer heat more efficiently.

Why does specific heat capacity matter?

Specific heat capacity is the amount of energy required to raise the temperature of a material by one degree Celsius. Materials with a higher specific heat capacity require more energy to heat up, so they will take longer to reach a desired temperature compared to materials with a lower specific heat capacity.

How does thermal conductivity affect heating rate?

Thermal conductivity is the ability of a material to transfer heat. Materials with higher thermal conductivity transfer heat more efficiently, allowing them to heat up faster compared to materials with lower thermal conductivity.

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