Tips for Heat Transferrence Lab

Lab Write Up #3: A Guide of Important Points and Procedures

Sorry this got kind of long,

In this lab we are attempting to discover what happens when you mix water together and whether we are able to create a mathematical model of what happens between two volumes of water of two different temperatures when mixed. We measured the temperature of the two bodies of water separately, noting their volumes as well, then we mixed the two together and again measured the temperature. If the two were the same volume we found that the mix of the two was the temperature in the middle of the two. This experiment again shows us that when two bodies of different temperatures are in contact, they exchange heat until both are the same temperature. When mixing water this exchange of heat can be very fast resulting in one body of water with one temperature throughout.

If the two bodies of water were not the same volume, we used the formula V1*T1+V2*T2/V1+V2 which is written more clearly on the Facebook page I think. We were able to predict the resulting temperature very accurately with this formula. This formula of course also works if the volumes are the same.

In this experiment we built a mathematical model of our experiment and figured out what 'should' happen and then found out that we were, in fact, able to show that when we performed the experiment, that what 'should' have happened actually did! We were able to go both ways, using the experiments to determine what happened and then developing mathematics which agree with our results, as well as using mathematics to predict future results.


Think about the different amounts of heat in the two waters, does 50ml of water have the same amount of "heat" as 100ml of water at the same temperature? How can we measure? Notice that in our equations we are using delta T or change in temperature so we can only measure how much heat is lost or gained during a change in temperature and not how much heat is in the body to begin with.


Things we assumed: Our mathematics assumes that it takes the same amount of heat to heat up 1ml of water 1 degree Celsius regardless of what temperature the water is at.

We assume that our thermometers were accurate to the degree.



We assume that no heat (Q) is lost or gained to the surroundings throughout the experiment and that only the water is transferring temperature. Which is to say that the Q gained by 1 body, is the same absolute value as the Q lost by another. Picture a red hot sword going from the forge to being dipped in water. The large amount of heat from the sword is transferred to the water which is a lower temperature (Heat tends to move from high temperatures to low temperature). Enough heat is transferred from the sword that the water near it boils and sizzles as it turns to steam, then the whole body of water warms up until the sword and the water are the same temperature. If you include the steam and sword and water, there is the exact same amount of heat in this system before you dip the sword as after, but it has become spread out between the sword, the water and the steam.

Energy and heat do not disappear and are never lost, only transferred. 
Energy tends towards a state of equilibrium, for heat, equilibrium is reached when things are the same temperature.


Other things we saw:
We saw that our temperature was often at least slightly different from what we expected. What are some of the reasons our numbers are not perfect?

We saw that if you change the substance from water to oil, our equation doesn't work anymore.

Musings:
 What does this say about the nature of oil. Does it take 1 Calorie to heat up oil 1 degree Celsius?


Are the points made in "Things We Assumed" true? How can you tell?

What does it say about us and the world that we are able to develop math which seems to be able to predict the future? Do we need to do labs anymore and couldn't we just do math? (People have always tried doing just the math and it tends to lead to false conclusions. Why?)

I could go on but I really should stop Sorry for getting a little rambly.