Question

To keep her soup warm Paheli wrapped the container in which it was kept with a woollen cloth. Can she apply the same method to keep a glass of cold drink cool? Give the reason for your answer.

Answer 1

Hint: Paheli can utilize the same woollen cloth to hold the cold drink chill as Woollen is a non-conductor and thus is a poor conductor of heat, so when it is covered around cold drink, it does not support the heat from outside to penetrate the glass, and in this way, it remains the drink cool.

Complete answer:
Wool is a bad conductor of heat because it catches a large amount of atmospheric air between its fibres. Thus, the yarn itself is not the insulator, but the air is.
When our palms or feet are freezing, it is enough to wear two thinner pairs of gloves/stockings than one deep pair because the layer of air caught between the two gloves/socks on every hand/foot performs as an extra insulator holding the heat produced by the body inside the gloves/socks somewhat of letting it out.
The wool or the wool-lined cloth acts as an excellent insulator of heat which means the transfer of heat energy is significantly less by the woollen cloth. This low transferal of heat energy by the woollen cloth supports retaining the warm soup's warmth because the woollen cloth reduces the escape of heat energy.
She covers a cold drink glass with a woollen material, the external heat energy will penetrate very slowly into the glass, and the cold drink will stay cool for a longer period. Wool is a poor conductor of heat, so it catches the air in between the woollen fibres as air is a lousy conductor of heat, minimizing the exchange of heat from the atmosphere. This way, it helps for getting the glass of cold drink warm respectively.
Yes, Paheli can utilize the same method to hold a glass of cold drink cool.

Note: Woollen clothes efficiently separate the body from atmospheric air by capturing a layer of air. Since both fibre and air are poor conductors of heat on fluctuating levels, it produces a separation that holds bodies warm. Woollen clothes are light, and there is not much air passage between the fabric. The air openings occupying between the fabric make us feel warm. Wool is a good insulator of heat, and the air holes in the fabrics block the passage of air from the surroundings into our bodies. This less motion of air through the woollen fabric assists us to keep warm.