(2-14)  Nefertiti proposes an experiment. She will mount a sharp stick at a fixed height on her bike. With you and the bike both stationary, she will prod you with the stick,  leaving a neat bruise on your torso. Then, having marked this as bruise number 1, you’ll repeat the experiment but this time it will be a ride-by prodding. You’ll stay where you are but this time, Nefertiti will get you as she is riding past at high speed, rather like a knight of old. Here's a picture:

Assume for the moment that length contraction happens in all directions, not just in the direction of relative movement of the reference frames. Now predict where the second bruise is going to be: