Calculating Area



		Area
		NB In pressure questions the area you have to consider is the contact* area.... this might well not be the whole area of the shape.... be careful!!* The area (A) is a measure of the two dimensional flat surface of a shape. The cross sectional area (csa) is the area of a slice through an object. For example the cross sectional area of a wire would be a circular shape. The surface area of an object is the minimum quantity of wrapping paper you would require to cover all of its sufaces. You will have come across this idea at Primary School and in your Mathematics lessons. In Physics you are expected to know how to find the area of some common shapes. You will be expected to remember (recall) how to calculate the basic (easy) ones: Other formulae will be given you to work from in the examination: UNITS The unit of area is the unit of length used in the calculation squared. The SI unit of length is the metre so the SI unit of volume is the metre squared (m²). Many calculations that you will be given up to GCSE level will involve centimetre squared and millimetre squared. Unless you are told otherwise do not attempt to change them into SI units.... if you do so and make a mistake you will lose marks. If you do change them do it carefully. Sketch the diagram below and work it out.... don't memorise it! The calculation of a number for an area is meaningless without the unit. It makes all the difference. A 1m² sheet of wrapping paper would wrap a very big present.... a 1 cm² sheet is smaller than a stamp.... a big difference! L O Jones (October 2001)

UNITS