ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: n.f on June 24, 2009, 07:32:07 pm
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Currently have a project set-up for the holidays and the teacher is away from the rest of term :S
I know which formula I need for my setup (balloons into water) but am not sure on exactly how to apply the formula
(http://upload.wikimedia.org/math/1/1/2/11231aee6af8b974a1bc4750b2f187e1.png)
My environment temperature (sink of water) is going to be constant at 10 degrees Celsius. so that is Tenv?
The initial temperature of water in the balloons is going to be 50 degrees Celsius so that is T0?
The surface area of the balloon is equal to A?
This setup is to run for 30 minutes to observe the rate of cooling.
and that is where my understanding stops.
Can someone please show working for a scenario of this?
Say a balloon with a surface area of 50cm squared and the above temperatures to determine the temperature after 30 minutes have passed
Thank you to anyone who can help
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Do you do spesh? Because they have a good explanation of Newton's Law of Cooling in the essentials textbook using differential equations.
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Nope, I'm only in year 11 and it isn't running this year :-\
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mm looks like this is not related to the specialist maths version of newton's cooling.
I suggest you take temperatures of the balloon over a time period, and plot the graph, then estimate the gradient. From there, you can see how h varies with time, and hopefully if the experiment works, see that h is related to the difference in temperature between the two bodies (water and environment).
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mm looks like this is not related to the specialist maths version of newton's cooling.
I suggest you take temperatures of the balloon over a time period, and plot the graph, then estimate the gradient. From there, you can see how h varies with time, and hopefully if the experiment works, see that h is related to the difference in temperature between the two bodies (water and environment).
Yeah, I'm planning to do 5 minutes interval checks over the time and then set up some plots. Thanks for your help. Were my assumptions above correct about Tenv and T0?
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Yes. Your variables are correct.
What is your experiment by the way? Are you trying to calculate h?
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does blowing on things actually cool them down?
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does blowing on things actually cool them down?
Indirectly. Increased fluid motion decreases the heat resistance of convective heat transfer from the surface to a fluid. This may increase rate of heat transfer overall (depending on if there are other limiting factors, such as poor heat conductivity through a solid), hence it cools faster.
<3 Chemical Engineering
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does blowing on things actually cool them down?
Indirectly. Increased fluid motion decreases the heat resistance of convective heat transfer from the surface to a fluid. This may increase rate of heat transfer overall (depending on if there are other limiting factors, such as poor heat conductivity through a solid), hence it cools faster.
<3 Chemical Engineering
<3 PHYSICS >:[
The same can be said for warming something up (i.e your hands). Amirite, Mao?
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Experiment is basically observing rates of cooling dependent on surface area. We have to relate it to some sort of calculations and my teacher suggested this formula.
I plan to submerge balloons filled with warm water into cold water and observe the different rates at which they change.
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does blowing on things actually cool them down?
Indirectly. Increased fluid motion decreases the heat resistance of convective heat transfer from the surface to a fluid. This may increase rate of heat transfer overall (depending on if there are other limiting factors, such as poor heat conductivity through a solid), hence it cools faster.
<3 Chemical Engineering
wow, i honestly didn't expect that. awesome, physics can be useful
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(http://www.ugrad.math.ubc.ca/coursedoc/math100/notes/diffeqs/mathgifs/cool_60.gif)
Found this formula which is derived from the original one I posted and it all works now. Thanks for those who helped