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प्रश्न
Iron rims are heated before they are fixed on the wooden wheels. Explain the reason.
उत्तर
The wooden wheels of a bullock-cart are fitted with iron tyres. To ensure a tight fit, the tyre is made slightly smaller in diameter than the wheel. The tyre is first heated due to which it expands. The heated tyre is then fitted on the wheel. When the tyre cools, it contracts and makes a tight fit on the wheel.
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