C489 Mountain stronghold

Fu Shengbing frowned slightly, and said: "Oh right, Old Zhao, there's something I don't understand. "When I bought the car, I saw that the salesman did hit the sandbag until it flew around randomly. The range of the sandbag was quite slow, but when you hit it, why didn't the sandbag move at all?"

I thought that Fu Shengbing was really observant, but she had some knowledge about mechanics