An industrial researcher investigates how the thickness of a mineral wool sleeve wrapped around a copper pipe containing hot oil affects its rate of thermal energy transfer.
The researcher writes this plan for their investigation:
State the independent variable in the researcher's investigation.
State the dependent variable in the researcher's investigation.
The table below shows the researcher's results:
| Thickness of mineral wool sleeve (mm) | Final temperature (∘C^\circ\text{C}∘C) | Temperature decrease (∘C^\circ\text{C}∘C) |
|---|---|---|
| 0 | 75 | 45 |
| 5 | 35 | |
| 10 | 28 | |
| 15 | 24 | |
| 20 | 24 | |
| 25 | 24 |
Complete the table by calculating the missing final temperatures of the oil.
Describe the relationship between the thickness of the mineral wool sleeve and the temperature decrease of the oil.
Suggest how the researcher could improve the reliability of their results.
