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Clothes—How Things are Made - Natural Fibres: Cotton, Silk, Wool, and Linen

Grade 5CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Fibre: A very thin, thread-like strand from which clothes are made. Fibres are twisted together to make yarn, and yarn is woven to make fabric.

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Classification: Fibres are classified into Natural Fibres (obtained from plants and animals) and Synthetic Fibres (man-made).

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Cotton: A plant fibre obtained from the 'bolls' (fruits) of the cotton plant. It grows best in black soil and warm climates. The process of separating cotton fibres from seeds is called Ginning.

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Linen: A plant fibre obtained from the stem of the Flax plant. The stems are soaked in water to soften them, a process called Retting.

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Wool: An animal fibre obtained from the fleece (hair) of sheep, goats, or camels. The process of removing the fleece is called Shearing.

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Silk: An animal fibre produced by the silkworm (Bombyx mori). The rearing of silkworms for the production of silk is called Sericulture. The silkworm spins a protective covering around itself called a Cocoon.

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Process Flow: The conversion follows the path: Fibre→SpinningYarn→Weaving/KnittingFabric\text{Fibre} \xrightarrow{\text{Spinning}} \text{Yarn} \xrightarrow{\text{Weaving/Knitting}} \text{Fabric}.

📐Formulae

Net Wool Yield=Total Weight of Fleece−Weight of Impurities (Grease/Dirt)\text{Net Wool Yield} = \text{Total Weight of Fleece} - \text{Weight of Impurities (Grease/Dirt)}

Total Fabric Area=Length×Width\text{Total Fabric Area} = \text{Length} \times \text{Width}

Total Yarn Needed=Yarn required per unit area×Total Fabric Area\text{Total Yarn Needed} = \text{Yarn required per unit area} \times \text{Total Fabric Area}

💡Examples

Problem 1:

A farmer harvested 850850 kg of raw cotton. After the process of ginning, 525525 kg of seeds were removed. What is the weight of the pure cotton fibre obtained?

Solution:

850−525325\begin{array}{r} 850 \\ - 525 \\ \hline 325 \end{array} The weight of the cotton fibre is 325325 kg.

Explanation:

To find the pure fibre weight, we subtract the weight of the seeds from the total weight of the raw cotton harvest using vertical subtraction.

Problem 2:

If 11 kg of raw wool contains 0.20.2 kg of dust and grease, how much clean wool will a factory get from 1010 kg of raw wool?

Solution:

Clean wool per kg = 1−0.2=0.81 - 0.2 = 0.8 kg. Total clean wool = 0.8×10=80.8 \times 10 = 8 kg.

Explanation:

First, we find the yield per kilogram by subtracting impurities, then multiply by the total quantity.

Problem 3:

A weaver uses 1212 metres of yarn to weave 11 square metre of linen. How many metres of yarn are required to weave 1515 square metres?

Solution:

Total Yarn = 12×15=18012 \times 15 = 180 metres.

Explanation:

We use the formula Total Yarn=Rate×Total Area\text{Total Yarn} = \text{Rate} \times \text{Total Area} to calculate the requirement.