Why are some glass cups made very thin? Will it crack?

All objects have the characteristic of thermal expansion and contraction, and the same goes for glass cups. When glass blooms in water, the temperature often reaches around 100 ℃, and glass is a poor conductor of heat, with thermal conductivity only 1/400 of steel. After pouring hot water into a glass, the inner wall of the glass is heated and expands faster than the outer wall, generating a significant outward expansion force that can cause the glass to break. If the glass cup is made thinner, the inner and outer walls of the glass will be heated and expand evenly, making it less likely to break. So, the glass cup is made relatively thin.