Investigate this Temperature can be measured on the Celsius, Fahrenheit and Kelvin scales. Find out how the Fahrenheit scale was developed. Compare it with the Kelvin and Celsius scales. Suggest why most scientists no longer use the Fahrenheit scale.
Fig. 8 Taking a child’s temperature using a digital thermometer.
Fig 9 Temperature is measured using a thermometer.
Temperature is measured using a thermometer. In the school laboratory you might use a spirit thermometer like the one in Fig. 9. As the liquid warms up it expands and rises up the tube. Thermometers like this contain mercury or coloured alcohol. You may also be familiar with the type of digital thermometer shown in Fig. 8. This is used for measuring human body temperature.
27.6 Area
Area is a measure of the size of the surface of an object. We calculate area using measurements of length. We can calculate the area of flat surfaces, such as a piece of paper as well as the surface area of three-dimensional objects, such as a football. Commonly used units of area are km2
(kilometres squared), m2 (metres squared), cm2 squared). Land is often measured in hectares. One hectare is equal to 10,000 m2
(centimetres squared) and mm2 .
(millimetres
Fig. 10 The area of flat surfaces (e.g. a photograph) and the surface area of 3D objects (e.g. a football) are calculated using measurements of length.
Calculating area 1. Rectangles and squares (e.g. one of your textbooks): Measure the length and the width to the nearest cm. Calculate the area by multiplying the length (l) by the width (w).
298
2. Irregularly shaped figures (e.g. the shape of your hand, or a leaf): Trace the outline of the figure onto squared graph paper. Then count the number of squares covered. Every square has an area of 1 cm2
