Thermal Properties of Matter

Second Day of Lab 02/26/2015

Created by: Khoi Luc

I. Introduction: 

Today our professor started off the class with the question: The ball is not small enough to pass through the ring. When the ring get heat up, does the ring get any bigger for the ball to pass through. The answer is YES!

That was how our class did some warm-ups.

II. Common Assumption:

Hypothesis: Our group had a little discussion on the topic of the ball and the ring. Here came the question: Does the ring expand in both direction, inwards and outwards, which also means that the hole inside the ring will have the same size? Or the ring just expands inwards. Based on the result of the experiment, our group concluded that the ring actually expanded outwards, so indeed the hole inside the ring got bigger.

Heating up the ring

III. Coefficient of Linear Expansion:

1. Heating up the rod

Introduction: We have rod that holds two small sticks of different metals in one end, specifically divac and brass. They both have the same lengths.

Question: When the professor transfers heat to the rod using the heat gun. Will the rod expand and bend? And in what way, towards the divac or brass, given that coefficient of brass is higher compared to divac

Hypothesis: Since the brass has greater coefficient, it will expand more and bend toward the divac side when the rod gets heat up.

Professor Mason is ready to heat up the rod

 

Conclusion: Our hypothesis was right. When the rod gets heat up, the metal has greater co-efficient will expand more and bend toward the other side.

2. Cooling off the rod:
Introduction: Here was how it went. The professor put the rod into the box of ice and let it sit there for a few seconds. Question: Will and how the rod bend?

Conclusion: Since the co-efficient of the brass is greater. The change in length of the brass will be greater, which means that the divac side will be longer and bend toward the brass side. Remark: this process is totally opposite to the heating up process.

IV. Angle under the rod

Introduction: Firstly, Professor Mason put the rod onto a cylinder at an 90 degrees. Question: When he heats up the cylinder, how much angle will change between the rod and the cylinder?

The set up

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Our derivation. Note: the formula theta= L_o*alpha*Delta over r is our final answer

A direct view of the set up

Using the Logger Pro. Professor Mason was finding the experimental result to verify if our answers was true or not. I will conclude my answer when I find out the propagation of uncertainty for theta.

Professor Mason was trying to analyze the graph of temperature vs angle 

Temperature increases over time.

Here is our work to find co-efficient of linear expansion of aluminum. Interestingly, the unit of the co-efficient is inverse K ( or inverse C)

V. My life is a lie:
Introduction: We were asked to draw the graph temperature v. time for water goes from below 0 degrees C to 100 degrees C. We confidently drew what we had learned in chemistry, a graph of steps, and were told the graph was false ?! Professor Mason explained that graph was just a simplified version, not an actual one.

Kudos for Jennie and Kathy to work their hands off to increase the temperature.

The actual graph is actually an exponential curve

The slope of the graph stands for dT/dt in the equation Power= Q/t= (m*c* dT) /dt

Here is our graph of water for temperature v. time. It turned out that this graph was not correct

Assigned Problem. This problem has heat of fusion involved

Blowing a Manometer

Practice problem

VI. Pressure in Manometer:
Introduction: We were given a manometer each group. Our job was to fill the manometer with water partially. Blowing and hold the breadth differently to demonstrate how different pressure has different effect on the column of water.

Here comes the formula:  pressure= density*height* earth's acceleration

Result: The greater the blow, the higher the column of water.

VII. Overall Conclusion:
We learned about thermal expansion, the relationship between change in temperature and time, the co-efficient of linear expansion, relationship between angle displacement and linear expansion, and introduction to new equipment-manometer.
VIII. Uncertainty and Error Propagation:

The answer is 9.35*10^-6