Temperature
WEEK 1
Topic: Temperature
Pupils should be able to
(i) compare the degree of hotness or coldness in degrees Celsius e.g. (a) my body’s temperature(b) the temperature in the classroom(c) the temperature of northern Nigerian and southern Nigeria(d) the temperature of the boiling water and the water in the normal room temperature
(ii) convert a given temperature in Centigrade to Fahrenheit using the Formula (9/5 X°C) +32
Study the following pictures
How does each of the situations feel on your body?
Oral activity
How will you describe each picture as stated below? The first has been done for you.
1. Boiling water in a kettle – very hot 2. Water coming out of the tap
3. Rainfall 4. Family fanning themselves 5. A glass of cold water
The activities above describe how hot or cold each of the situations is. This is called
temperature.
The degree of hotness or coldness of an object is known as temperature.
To measure temperature, we use a thermometer. When the temperature of an object
changes, the liquid in the thermometer moves up or down. Temperature is measured in
degrees Celsius (or centigrade) ºC or degrees Fahrenheit (ºF).
Mercury thermometer
-10 0 10 20 30 40 50 60 70 80 90 100 110 °C
28°C
The thermometer above is called a mercury thermometer. It is used in measuring the
temperature of water, air and other liquid. It is graduated in 10 degrees i.e. 0, 10, 20 …
The thermometer drawn above ranges from –10ºC to 110ºC. There are five divisions
between any two numbers of the thermometer dr
above. Thus, each division equals 2ºC Water boils at 100ºC.This is also 212ºF(100ºC = 212ºF).
RELATIONSHIP BETWEEN DEGREES CELSIUS AND DEGREES FAHRENHEIT.
The diagram below shows the temperature scales for degrees Celsius and degrees
Fahrenheit.
The Fahrenheit and Celsius scales are different.
The boiling point of water is at 100ºC or 212ºF.
The freezing point of water is at 0ºC or 32ºF.
On the Celsius scale 0ºC and 100ºC are 100 divisions apart, while on
the Fahrenheit scale 32ºF and 212ºF are 180 divisions apart (212–32 =
180). That implies that 100 degrees on the Celsius scale are equivalent to
180 degrees on the Fahrenheit scale.
100 Celsius units = 180 Fahrenheit units
1 Celsius unit = 180/100 Fahrenheit unit
= 1.8 Fahrenheit unit
= 9/5Fahrenheit unit
10 Celsius units = 9/5× 10 = 18 Fahrenheit units
From the temperature scale, we can see
:0ºC = 32ºF (95× 0 + 32 = 0 + 32 = 32)
10ºC = 50ºF (95× 10 + 32 = 18 + 32 = 50)
20ºC = 68ºF (95× 20 + 32 = 36 + 32 = 68)
Therefore, temperature from degree Celsius (ºC) to degree Fahrenheit (ºF) is given as:
F = 9/5× C + 32 F = 9 C/5 + 32
Subtract 32 from both sides:
F – 32 = 9 C/5
Multiply both sides by 9/5
5/9(F – 32) =9 C/5 ×5/9 C =5/9(F – 32)
Examples
1. Here 40ºC is converted to degrees
Fahrenheit.
Solution
F = 9/5× C + 32
= 9/5× 40 + 32
= 72 + 32 = 104
Therefore, 40ºC = 104ºF
2. Here 95ºF is converted to degrees
Celsius.
Solution
C = 5/9(95 – 32)
= 5/9× 63
= 35
Therefore, 95ºF = 35ºC
Exercise
A. Convert these temperatures to degrees Fahrenheit.
1. 25ºC 2. 15ºC 3. 17.5ºC 4. 80ºC 5. 0ºC 6. 30ºC
7. 12.5ºC 8. 100ºC 9. 1000ºC 10. 450ºC 11. 75ºC 12. 1250ºC
B. Convert these temperatures to degrees Celsius.
1. 77ºF 2. 68ºF 3. 392ºF 4. 158ºF 5. 122ºF 6. 149ºF
7. 176ºF 8. 221ºF 9. 1472ºF 10. 806ºF 11. 950ºF 12. 1750ºF
temperature is the degree of hotness or coldness of an object
the instrument used in measuring (checking) temperature is the thermometer
the mercury thermometer is used to check room or air temperature
the clinical thermometer is used to check human body temperature
the maximum and minimum thermometer is used to check the lowest and the highest
the temperature at a weather station
on the temperature scale, degrees Celsius can be converted to degrees Fahrenheit
and vice versa
to change the temperature from degrees Celsius to degrees Fahrenheit use this
formula:
F = 9/5× C + 32
the temperature from degrees Fahrenheit to degrees Celsius is given as
C = 2/9(F – 32).
Revision exercise 22
1. The table below shows the normal temperature (ºC) in Lokoja for a
six-month period.
Month Monthly (ºC) temperature
April 28.9
May 28.3
June 22.2
July 33.4
August 22.2
September 29.4
Answer the following questions:
a) Which month had the highest temperature? b) Which months had the same temperature?
c) Which were the coldest months? d) By how much was September hotter than April?
e) What was the average temperature for the six months
2. Convert these temperatures to degrees Fahrenheit.
a) 15ºC b) 28ºC c) 125ºC d) 305ºC
e) 7.5ºC f) 15.5ºC g) 45ºC h) 18.5ºC
3. Convert these temperatures to degrees Celsius.
a) 113ºF b) 86ºF c) 68ºF d) 131ºF
e) 158ºF f) 284ºF g) 599ºF h) 680ºF