The charm quark is similar to the up quark because of its +2/3 electric charge and the strange quark is like the the down quark because of its -1/3 electric charge.

Just to clarify this analogy further, hold the pen vertically in front of you with the tip pointing up. Imagine an axis running through the pen from the tip to the bottom and spin the pen around this axis by holding it straight with one hand and twisting the bottom of the pen with the other. Now, still twisting the pen in this manner, hold the bottom of the pen still and trace out a horizontal circle in the air. By twisting the pen as before but also rotating the tip, the spin axis is now precessing or wobbling. This is analogous to the precession of the muon's spin.

If you would like a link to a video which demonstrates how a spinning top wobbles, please go to our podpage.