As was said in the preface to the predecessor of this book (200 Puzzling Physics Problems, Cambridge University Press, 2001), an understanding of the laws of physics is best acquired by applying them to practical problems. Many of the corresponding solutions, however, require routine, but perhaps long and boring, calculations, which tend to deter even the most curiosity-driven students of the subject. This book, like its antecedent, aims to show that not all physics problems are like that, and that a bit of careful thought, a little ingenuity and a flash of insight can go a long way.

Although we have aimed to place as many problems as possible in settings that will be familiar to, and easily understood by, most people (not just physics students and their professors), some have had to be somewhat artificially constructed in order to bring the physics involved to the fore. However, that said, many of these contrived situations can be set up in a laboratory, and theory can be tested against experiment. Even so, some ‘test areas’, especially those in outer space, and some apparatus, in particular a copious supply of infinitely long rods, were beyond the resources available to us!

Nevertheless, we hope that you will be intrigued by questions such as:

1. • How do you maximise the gravitational effect of a lump of plasticine?

2. • How does a spoked wheel appear in a photo-finish picture?

3. • What happens when a suspended Slinky is suddenly released?

4. • How can your square-on reflection in a plane mirror show your closed eye, but not your open one?

5. • How long is it before Santa Claus is discharged?

6. • Does an electromagnetic field carry angular momentum?

7. • What is the path of a ball rolled onto a rotating turntable?

8. • How much charge flows when a magnet is dropped through a metal loop?

9. • Where should you park your car to avoid a frosted windscreen?

10. • How large is the force between end-to-end solenoids?

11. • How do you bring about ‘the parting of the waters’ in a Florence flask?

12. • When does an Euler strut go phut?

13. • What is the pressure produced by a neutron in a box?

14. • How long is an ‘infinite electronic chain’? Does it matter?

15. • How much harder is it to steer a car with flat tyres?