Larry Scheckel was a high school physics and aerospace teacher for almost 40 years, and he wrote a book called Ask a Science Teacher: 250 Answers to Questions You've Always Had About How Everyday Stuff Really Works that answers common questions on a wide range of topics.
Why are we attracted to unhealthy foods? How does your heart pump? Why is chickenpox so much worse for adults than it is for kids? What is the lowest temperature known in nature? How does the moon affect the ocean tides? Why can't we create a perpetual motion device? Why don't school buses have seatbelts? What is quantum physics? Who or what built Stonehenge?
The answers (they are 1-3 pages long) are clearly written, and filled with fun insights and anecdotes. This is a fantastic book for a curious kid or an adult such as myself who likes to learn how the world works.