Thermal Expansion

Purpose:  This experiment is composed of various experimental examples that test the expansion of various materials when these materials experience a significant change in temperature. Through these examples, we will determine if the theoretical application of thermal expansion is consistent with the behavior of objects in the physical world.

Thermal Expansion of a Ring

We begin our experimentation by observing a metal ring and a metal sphere. Initially, we are not able to put the metal sphere through the metal ring, but after the ring is heated, it expands and the result is that we are able to push the metal sphere through the metal ring.

How Does The Ring Expand?

We hypothesize that the reason the metal ring expands outwards has to do with the atoms of the object and the behavior of its electrons. The hole of the ring gets larger, not smaller.

Thermal Expansion of a Bimetallic Strip

Before we examined the behavior of a bimetallic strip going through a change on temperature, we hypothesized the behavior of the bimetallic strip. We argued that the behavior of the strip would be reliant on the coefficient of thermal expansion, or the material's ability to attain heat, since the the strips are similar in size and temperature change.

We look at the behavior of thermal expansion of a bimetallic strip. A bimetallic strip is a strip composed of two different metals, perhaps copper and invar, that has the same length. When heated, the bimetallic strip curves toward the metal that has the lower coefficient of linear expansion.

We, again, examine the behavior of the bimetallic strip, but instead of exposing the strip to a torch, we dump it in ice. The strip curves toward the metal with the larger coefficient of thermal expansion.

Thermal Expansion of a Rod

We look at a traditional example of linear thermal expansion of a rod. It is being held firmly by a support pole on one end and lays on an instrument that can measure displacement in radians on the other end. 

Using the theoretical equation of linear thermal expansion, we solved for the anticipated change in length and created a relationship for meters to radians so that we may confirm the measured change in length to our theoretical value of change in length.

Using logger pro equipment, we were able to determine the change in length in radians. Our graph shows as temperature rises, the length changes.

Uncertainty For Coefficient of Linear Expansion of The Rod

Temperature as Ice Water Is Heated

The rate at which temperature changes shows that temperature does not remain constant during phase changes. For example, as ice melts, some of the new water is heated while in the ice and increases in temperature and the dominant temperature of the ice mixed with the temperature of the water averages to show a gradual change in temperature.

Our drawing represents what we thought happens with temperature when it goes through phase changes. Our drawing ended up being incorrect, as temperature gradually changes throughout the entire process. Temperature does not remain the same during phase change. We also show some calculations for the heat of fusion of water

Pressure Through a Tube

We preform an experiment where we measure distances and calculate how much pressure was introduced in the tube by mouth.

Using formulas for pressure, we calculated the pressure through a tube with the distances we measured by hand.

Calculations For Mass

We were given a problem for solving the mass of water needed to turn completely into ice with a final temperature of zero when mixed with some ice at -12 degrees Celsius.

Conclusion:   We have confirmed that thermal expansion expands outward without contracting, as demonstrated with a ring. If cooled, an object can contract. This is consistent with our theory of thermal expansion, as our change of temperature can be positive or negative. During the experiment of thermal expansion of the rod, we calculated the value at which the rod expands and compared our calculation with the value received on Logger Pro. Our calculations were off slightly, as the measured values were roughly measured, so we propagated to account for any uncertainty. We also discovered that our traditional believe of temperature during phase change is misleading. Our textbooks tell us that temperature remains constant during the phase change process when in actuality, temperature continues to change during this process.