Relative Motion

Take a Message Soldier

Age 14 to 18 Challenge Level:

A messenger runs from the rear to the head of a marching column and back. When he gets back, the rear is where the head was when he set off. What is the ratio of his speed to that of the column?

Mach Attack

Age 16 to 18 Challenge Level:

Have you got the Mach knack? Discover the mathematics behind exceeding the sound barrier.


Age 16 to 18 Challenge Level:

Calculate the paths of raindrops flying up from the back tyre of a bicycle

Which Twin Is Older?

Age 16 to 18

A simplified account of special relativity and the twins paradox.