The floating melons sink and the plums sink, and I spend the summer with a book on my pillow.

How to spend the long time in the hot summer? It’s a good choice!

Floating melons and sinking plums refer to watermelons floating on the surface and plums sinking to the bottom of the water. It refers to eating melons and fruits soaked in cold water to relieve the heat, which is a metaphor for the pleasure of cooling off in summer.

From Cao Pi of the Three Kingdoms Wei Dynasty's "Wu Zhishu with Chaoge Ling": "Sweet melons float on clear springs, and plum blossoms sink on cold ice."

Why are watermelons so big and heavy? The water surface; the plums are small and light, but they sink to the bottom of the water?

Mainly because of the buoyancy of water. Watermelons have low density and gravity is less than buoyancy, so they float. Plums are dense and their gravity is greater than their buoyancy, so they will sink.

My knowledge of physics has increased, and I feel quite naked...