题目

Singing had always been an important part of Gloria Estefan’s life. “Since I was three years old, I sang. I sang everything,” Gloria said. “Cubans,” she added, “are a musical people”. Gloria was born in Cuba in 1957. Her family left the country just before Fidel Castro came to power. In Miami, where the family settled, many people did not accept Cuban immigrants. In first grade, she spoke little English, but she worked hard to learn the language. Six months after she entered school, she won an award for reading in English! When Gloria was ten, her father returned from the Vi漂浮在水面上的木块，静止时有1/5的体积露出水面，若在木块顶部放一质量为1kg的铁块，刚好使木块浸没水中，求：（1）木块密度？（2）木块体积？