Yesterday I was reading something. I feel like I wanted a drink, so I went to kitchen and delighted to see that there was 1.5 litres pepsi bottle waiting for me. I tried to open it but unable to open. I asked my father to open it but he said that I should know how to open it. He told me a great trick that take some water and heat it and than pour it on the cap of bottle. I did and become very surprised to see that bottle was now opened easily. I become very curious that how it works? I asked my father that how this happen. He said that when we heat any matter it increases in volume. This phenomenon is known as THERMAL EXPANSION. I asked the mechanism of it. He said that as we all know that matter is made of atom and molecules. So when we heat the molecules vibrate faster and faster and thus they become separated. As they separated a space is formed between all molecules so the matter changes it size. I thanked my father to give me information and now I’m ready to have a drink.