### Speedy Sidney

Two trains set off at the same time from each end of a single straight railway line. A very fast bee starts off in front of the first train and flies continuously back and forth between the two trains. How far does Sidney fly before he is squashed between the two trains?

### Illusion

A security camera, taking pictures each half a second, films a cyclist going by. In the film, the cyclist appears to go forward while the wheels appear to go backwards. Why?

### Walk and Ride

How far have these students walked by the time the teacher's car reaches them after their bus broke down?

# An Unhappy End

##### Age 11 to 14Challenge Level

Two engines are 1000 metres apart at the ends of a single track railway line.

They set off towards one another at 10 metres/second.

Just at that moment, a fly sitting on the front of one of the engines sets off and starts to fly along the railway line at 25 metres/second.

The fly eventually meets the front buffer of the other engine which by now has travelled some way along the track.

The fly immediately turns round and flies at its usual speed towards the first engine.

When it gets there it turns round again and flies back towards the other engine, and so on, and so on...

How far will the fly have travelled before the unhappy end?