3.Rubber band on stretching breaks down. Why?
Answers
Answer:
When molecules form crystals they give off heat hence the reason the rubber band gets hot when stretched. When you let go of the rubber band the polymer molecules break out of the crystals. Whenever molecules break out of crystals they absorb heat hence the reason the rubber band now goes cold.
Rubber Band on Stretching Breaks Down Beyond Its Elastic Limit
Explanation:
A rubber band can only stretch as far as its elastic limit, which is dependent upon its thickness and quality. When stretched beyond this limit, the rubber band breaks. So, elasticity of a rubber band is determined by the amount of weight in grams required to stretch it to its elastic limit.
As the rubber is stretched the bonds between adjacent chains are broken. Stretching a rubber band makes it get hot, heat energy is lost, hence the reason the rubber band gets hot when stretched.
When you let go of the rubber band the polymer molecules break out of the crystals, whenever molecules break out of crystals they absorb heat hence the reason the rubber band now goes cold. Therefore, if you put heat energy into a rubber band it will get shorter, unlike most materials when they are heated.