Imagine you hold one end of a slinky or a coiled spring and a friend holds the other end to maintain some tension. You move your hand quickly towards your friend to create a disturbance that moves towards him along the slinky. Now imagine moving your hand quickly
perpendicular to the slinky. Finally, imagine creating a disturbance that is partly along the slinky and partly perpendicular (moving your
hand diagonally). What would happen to this disturbance if the transverse part and the longitudinal part traveled at different
speeds?
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