Heat Transfer Investigation
A teacher asks students to touch their plastic tabletop and then touch the metal leg of their chair. When asked which one is colder, the students respond that the leg is colder. The teacher then uses an infrared thermometer to determine the temperatures. Much to the students' surprise, the metal chair leg and the plastic tabletop are the same temperature. The teacher asks, "Why is it that metal objects generally feel cool or cold while plastic objects feel warm when they're the same temperature?" The class decides to investigate this phenomenon.
Group 1
Source 1.1
As an introduction to understanding this phenomenon, students investigate the heat characteristics of three samples from three different substances.
- The samples of the substances were placed in a freezer overnight.
- The next day, they were taken out of the freezer and placed on the same surface.
- The temperature of each sample was taken immediately and again after 20 minutes.
- The students calculated the change in temperature over the 20 minutes for each sample.
The results are shown in the tables.
Substance 1
| | Sample 1 | Sample 2 | Sample 3 | |-------------|----------|----------|----------| | Mass (g) | 50 | 100 | 150 | | Temperature Change (°C) after 20 minutes | 37 | 23 | 18 |
Substance 2
| | Sample 1 | Sample 2 | Sample 3 | |-------------|----------|----------|----------| | Mass (g) | 75 | 150 | 225 | | Temperature Change (°C) after 20 minutes | 41 | 32 | 18 |
Substance 3
| | Sample 1 | Sample 2 | Sample 3 | |-------------|----------|----------|----------| | Mass (g) | 50 | 100 | 150 | | Temperature Change (°C) after 20 minutes | 49 | 36 | 24 |
Question 1a
Explain why metal objects generally feel cooler than plastic objects even when they are at the same temperature.
Group 2
Source 2.1
The teacher explained that heat moving into objects that touch is called conduction. The class wanted to investigate conduction to help them understand what they observed about the different substances. They decided to investigate how temperatures change when different substances touch.
They began by investigating how a heated metal block changed the temperature of a table it was placed upon. They repeated this investigation with a cooled metal block.
Heated Metal Block
| Time (min) | Metal Block Temperature (°C) | Table Temperature (°C) |
|---|---|---|
| 0 (start) | 200 | 20 |
| 5 | 120 | 70 |
| 10 | 107 | 79 |
| 15 | 98 | 85 |
| 20 | 87 | 87 |
Cooled Metal Block
| Time (min) | Metal Block Temperature (°C) | Table Temperature (°C) |
|---|---|---|
| 0 (start) | 0 | 20 |
| 5 | 5 | 19.5 |
| 10 | 11 | 19 |
| 15 | 16 | 18.5 |
| 20 | 18 | 18 |
Suzanne made a claim that much less energy was transferred during the cooled metal block investigation than when the block was heated.
Question 2a
Discuss Suzanne's claim about energy transfer during the cooled metal block investigation compared to the heated block investigation.
Teach with AI superpowers
Why teachers love Class Companion
Import assignments to get started in no time.
Create your own rubric to customize the AI feedback to your liking.
Overrule the AI feedback if a student disputes.