ok i post one. quite easy
a man is going through a train tunnel.
when he's 1/4 thru the tunnel he heard a train whistle.
if he turn back towards the entrance the train will miss him by
a slight bit.
if he were to run towards the other end the train will oso miss
him by a tiny bit.
assuming this guy constantly moves at a top speed la, hw fast is
the train going compared to him?