A student investigated the heat loss of piglets in drafty vs insulated environments using metal cans wrapped in synthetic fleece to represent the animals. One can was placed in front of a ventilation fan (representing drafty conditions) and another was placed inside an insulated polystyrene box (representing insulated conditions). Both cans were filled with the same volume of hot water and their temperatures were recorded at intervals of 20 minutes over 40 minutes. This was repeated for five trials. The results are shown below:
| Trial | Drafty - 0 min | Drafty - 20 min | Drafty - 40 min | Insulated - 0 min | Insulated - 20 min | Insulated - 40 min |
|---|---|---|---|---|---|---|
| 1 | 80 | 54 | 36 | 80 | 68 | 58 |
| 2 | 78 | 51 | 33 | 78 | 65 | 55 |
| 3 | 81 | 55 | 37 | 81 | 69 | 59 |
| 4 | 79 | 52 | 34 | 79 | 66 | 56 |
| 5 | 82 | 56 | 38 | 82 | 70 | 60 |
(i) How many times did the student measure the temperature of the water in the cans under drafty conditions during the investigation?
(ii) The diagram below shows one of the temperature readings during the investigation.
Use the diagram and the information in the table to complete the following sentence:
"The reading on this thermometer is 65∘C65^\circ\text{C}65∘C, which suggests the reading was taken from a can after 202020 minutes kept under insulated conditions."
(i) What was the independent variable (the variable that the student chose to change) in this investigation?
(ii) What was the dependent variable (the variable measured by the student) in this investigation?
(iii) Explain why the student kept other variables constant.
Give one way that the student could make his temperature measurements more accurate.
The results of this investigation suggest that pork (meat) production would be less efficient if farmers kept their piglets in drafty, uninsulated pens rather than insulated ones. Use the data and your biological knowledge to explain why.
