worksheet and assessment card masters - National STEM Centre

·Effect of wetting
on thermal insulation·
NUFFIELD
HOME ECONOMICS
FIBRES AND FABRICS: .
WORKSHEET
F,M5a
WHY SHOULD YOU KEEP YOUR FEET DRY? 2 Fit the covers over two of the boiling-tubes.
YOU WILL NEED:
6 fabric pieces, 10 cm X 10 cm - woven or knitted fabric,
e.g. wool or acrylic jersey
Detergent
Water
Clock or watch with seconds hand
4 boiling-tubes in stand
3 thermometers, -10 °c to 110 °c, fitted through corks
Boiling-tube holder
Kettle
Tray to catch spills
Glass rod
Needle and thread
Labels
3 different coloured pens
1 Make identical covers for two boiling-tubes using
three layers of fabric as shown below.
three pieces of
woven or knitted
fabric
Fold the three layers
of fabric in half and
.. stitch to make a close
fitting cover for the
boiling-tubes
3 Label the holes in the boiling-tube stand A, B, C,
and D. Put the two covered boiling-tubes into holes B
and C and the two that remain into holes A and D.
thermometer
cork
boiling-tube
A
'-
B
fabric
cover
'--
c
4 Carefully fill the four boiling-tubes to within 3 cm
of the top with boiling water. Fit the corks and
thermometers to A, B, and C.
5 Use a clock or watch and record your readings every
two minutes in a tabl~ like the one below.
Time (minutes)
Temperature, boiling tube A
Temperature, boiling-tube B
Temperature, boiling-tube C
6 After six readings have been taken, use the glass rod
to add one drop of detergent to boiling-tube D.
7 Hold boiling-tube C over a tray with the holder and
pour the contents of D onto the fabric. Put C back into
its hole in the stand. Continue to take a further five
readings and record your results.
What did you notice about the immediate effect on the
temperature of wetting the fabric?
8 Plot your results on the graph on worksheet FM5b.
Use a different colour to represent each boiling-tube -
red forA, 'blue 'for B; and 'green forC. "
o
© 1984 Nuffield-Chelsea Curriculum Trust
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D
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