| 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
the 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) |
