Science, Maths & Technology

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Everyday maths 1

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# 5.2 Understanding temperature

Using the right temperature is often a matter of safety. For example, a piece of machinery may not be able to operate properly below a minimum temperature or above a maximum temperature, or a jar of tablets may include advice on its label about what temperature it should be stored at.

Figure _unit3.5.6 Figure 41 Warning labels

Temperatures used to be shown in degrees Fahrenheit. You will still see these measures sometimes. For example:

Figure _unit3.5.7 Figure 42 Temperatures in Celsius and Fahrenheit

## Box _unit3.5.2

Note: Fahrenheit is still used in the USA.

Here are some temperatures in Celsius and Fahrenheit:

Table _unit3.5.1
Celsius Fahrenheit
–18 0
0 32
10 50
20 68
30 86
40 104
50 122

Take a look at the example below for comparing temperatures.

## Case study _unit3.5.2 Example: Safe storage

You have instructions with chemicals sent from the USA that they must be stored at between 50 and 70°F. The thermometer on the storage tank shows the temperature in degrees Celsius.

Figure _unit3.5.8 Figure 43 Using a thermometer in safe storage

Are the chemicals stored safely?

### Method

Looking at the temperature comparison chart, 13°C falls in the following range:

• 10°C = 50°F
• 20°C = 68°F

13°C falls between 10°C and 20°C, meaning that it is also in the range between 50°F and 68°F. The chemicals are stored safely.

Now try the following activity. Remember to check your answers once you have completed the questions.

## Activity _unit3.5.2 Activity 13: Celsius and Fahrenheit

1. A recipe for meringue says you must cook it at 150°C. Your cooker shows temperatures in Fahrenheit. What should you set it to? (Use the conversion chart below to help you.)
Table _unit3.5.2
Celsius Fahrenheit
100 212
150 302
200 392
250 482
300 572
350 662
1. The thermometer on an old freezer shows the temperature in degrees Fahrenheit.
Figure _unit3.5.9 Figure 44 Converting temperatures on old thermometers

A pack of food has a warning that it must be stored between –12°C and –25°C. Is the food stored safely? (Use the conversion chart below to help you.)

Table _unit3.5.3
Celsius Fahrenheit
–30 –22
–20 –4
–15 5
–10 14
–5 23
0 32
10 50
1. A machine must be turned off if the temperature rises above 600°F. Using a Celsius thermometer, you find out that the temperature of the machine is:
Figure _unit3.5.10 Figure 45 A thermometer

Is it safe to leave it turned on? (Use the conversion chart below to help you.)

Table _unit3.5.4
Celsius Fahrenheit
0 32
50 122
100 212
150 302
200 392
250 482
300 572
350 662
400 752