What If? by Randall Munroe
Randall Munroe is the creator of the web comic xkcd.com, home of all geeks sufficiently socialised to have a sense of humour. In this book he applies rigorous* logic to analyse the often weird questions people ask him.
Questions like “Is it possible to build a jetpack using downward-firing machine guns?”, “From what height would you need to drop a steak for it to be cooked when it hit the ground?” and “Is there enough energy to move the entire current human population off-planet?”. Curious? Intrigued? Read the book!
* May not actually be rigorous.