worksheet and assessment card masters - National STEM Centre

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Fabric cling and· anti-stat· WHAT MAKES CLOTHES CLING? YOU WILL NEED: . Selection of fabrics Poli~ed plate of stainless steel bent at an angle of 70° one-third from the end Rubber or cork. mat Bulldog clip Small block of wood Length of wire Plastic or wooden tweezers or spatula Fabric softener (e.g. Comfort) Watch or clock with seconds hand Access to tap fabric sample 1 Clamp a strip of fabric to the steel test plate. With a piece of brushed nylon wrapped round a block of wood, rub the fabric a number of times. Count the number of rubs you give the fabric. 2 Tip the test plate onto its shorter side and earth it with a length of wire to a cold water tap. Does the fabric cling to the plate? 3 Every thirty seconds, pull the fabric away from the plate with the tweezers. Do this until the fabric has lost its cling. Note the time this took. + + + + bulldog clip fabric + sample + wire to cold water tap (earth) NUFFIELD HOME ECONOMICS FIBRES AND FABRICS: WORKSHEET FM17b 4 Repeat these tests using a different type of fabric. Remember t6 rub the 'same number of times for each fabric. 5 Record your results and compare them with the triboelectric series on worksheet FMl 7a. What do you find? 6 Rinse the fabric specimens in Comfort or some other fabric softener. Dry them and repeat the test. Record your results. What do you find? steel plate fapric " s~mple bulldog clip wire to cold water tap (earth) © 1984 Nuffield-Chelsea Curriculum Trust
Surface tension and detergents A drop of water is made of millions of tiny particles called molecules. These are attracted to each other; so each molecule tries to get as close to the other molecules (and therefore the centre of the drop) as possible. Around the edges of a drop of water the molecules are only attracted into the drop and not outwards, so the drop stays round and whole. If you break the surface, the drop will collapse because you have broken its surface tension, that is, you have attracted the molecules away from the centre. HOW CAN SURF ACE TENSION BE REDUCED? YOU WILL NEED: Small pieces of water-repellent cloth, e.g. old mackintosh, or tightly woven wool worsted Washing-up liquid Dropper Thin glass rod Needle and tweezers Bowl of water 1 Pick up a needle with the tweezers and carefully lay it onto the surface of the bowl of water. 2 Dip the glass rod into some washing-up liquid. 3 Touch the surface of the water with washing-up liquid. Take care not to disturb the needle. needle on surface of water ~ter with washing-up liquid What happened to the needle? Explain what you saw. How could you test your idea? NUFFIELD HOME ECONOMICS FIBRES AND FABRICS: WORKSHEET FM18 4 Lay the piece of water-repellent cloth flat on a table. Use your dropper to spot it with four separate drops of water. 5 Pick up a little degergent on the end of the glass rod and use it to touch two of the water drops. Leave the other two alone. water-repellent cloth touch two water drops with quid ~ washing-up li~ Did the detergent make the water droplets collapse? . What happened to the cloth just below the droplets? How could you test your idea? © 1984 Nuffield-Chelsea Curriculum Trust
Page 1 and 2: FIBRES i\.ND ,ABRICS WORKSHEET AND
Page 3 and 4: Suppose you have collected some dat
Page 5 and 6: Why do we have curtains and carpets
Page 7 and 8: Note. It is essential to examine fi
Page 9 and 10: Effect of wetting on thermal insula
Page 11 and 12: Spinning, knitting:, and • weavin
Page 13 and 14: Spinning, knitting, and • weaving
Page 15 and 16: WHAT MAKES UP WHITE LIGHT? If you s
Page 17 and 18: Colour fastness of household dyes W
Page 19 and 20: Colour fastness of curtain fabric W
Page 21 and 22: All wool fibres have a protective c
Page 23: fabric cling and anti-stat Garments
Page 27 and 28: 1 Which is the odd one out in each
Page 29 and 30: 1 Rewrite the following two lists p
Page 31 and 32: 1 Underline the odd one out. The qu
Page 33 and 34: 1 Select the odd one out in each of
Page 35 and 36: In questions 1, 2, and 3, select th
Page 37 and 38: In questions 1, 2, and 3, select th
Page 39 and 40: 1 We all have constant contact with

worksheet and assessment card masters - National STEM Centre

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