Exp 2 Kwon.docx

IV. RESULTS AND DISCUSSION: Specimen

Lo (cm)

Brass

To (°C)

Lf (cm)

35cm

22.4°C

Copper

35cm

Aluminum

35cm

Tf (°C)

∆L (cm)

∆T (°C)

34.95cm

100°C

0.049cm

77.6°C

26.1°C

34.95cm

100°C

0.045cm

73.6°C

26.4°C

34.95cm

100°C

0.047cm

73.6°C

Specimen

αexperimental

αtheoretical

Percentage Error

Brass

1.8 x 10-5

1.9 x 10-5

5.26%

Copper

1.7 x 10-5

1.7 x 10-5

0%

Aluminum

1.8 x 10-5

2.3 x 10-5

21.74%

Using the formula

α=

𝐿𝑓−𝐿𝑜 𝐿𝑜(𝑇𝑓−𝑇𝑜)

=

∆L 𝐿𝑜(∆T)

∆L

∆T

Brass

∆L= Lf – Lo

= 0.049

= 77.6°C

Copper

∆L = Lf – Lo

=0.045

= 73.6°C

Aluminum

∆L = Lf – Lo

=0.047

=73.6°C

We have received certain percentage error between theoretical results from experimental. There are metals that have expanded and some have contracted. There is also metal that didn’t have any changes at all.

V. CONCLUSION: Based on the data that we gathered from the experiment on obtaining the coefficient of the linear expansion of brass, copper and aluminum, we have observed that there is contraction instead of expansion. Thermal expansion was generally defined as the increase in the volume of a material as its temperature which is increased that is usually expressed as a fractional change in length or volume per unit temperature change; a linear expansion coefficient is usually for the expansion of a solid, while a volume expansion is for a liquid or a gas. Correlating this to the experiment, the materials having a change in temperature will have a corresponding change in a particular dimension which is length for this experiment. The expansion of a material depends on the value of its coefficient of linear expansion; wherein higher the coefficient of linear expansion is, the more it will expand and with that it can be considered that these two are directly proportional. From the data

gathered, aluminum has greater change in length than copper. So therefore, we can conclude that an object with greater coefficient of linear expansion will have the greater change in length as well. Aside from the coefficient of linear expansion, there are other factors that affect the change in length of a material in thermal expansion and these are the initial length of the body and the change in the temperature. All these three factors are directly proportional to the change in length of the material and an increase in value to these would correspond to a change in length wherein it will also increase.