Activity 3. Air pressure in a closed volume versus its temperature
Sometimes we see hot air balloons “flying” in the sky. The way they rise is simple. The hot air exerts more pressure on the inner surface of the balloon than the air pressure on its outer surface. The balloon becomes lighter, and as a result, rises to a height at which the pressures equalise.
A simple experiment measured the air pressure in a closed volume as a function of its temperature. The measured values are recorded in the table. Examine the table and solve the problems. Record your answers on the worksheet provided.
| t (o C) |
p (hPa) |
|
22,8 |
1 027 |
|
25,1 |
1 028 |
|
27,8 |
1 030 |
|
30,3 |
1 032 |
|
34,4 |
1 034 |
| 39,2 |
1 035 |
|
43,3 |
1 038 |
| 47,4 |
1 041 |
| 52,3 |
1 044 |
|
55,8 |
1 047 |
|
59,4 |
1 050 |
| 67,8 |
1 054 |
|
72,1 |
1 057 |
| 74,0 |
1 058 |
| 74,2 |
1 059 |
- Study the data from the table and answer the following questions:
- In what units is air temperature expressed? In what units is air pressure expressed?
- What was the maximum temperature the air reached?
- Do you see any relationship between the temperature of air and its pressure in a closed volume? What is this relationship?
- Create a graph that illustrates the link between temperature and pressure using the values in the table. The graph can be done in Excel.
To download: Worksheet. Activity 3
