The displacement (in cm) of a mass-spring system is given by y = 2.0 cos(15t). what "distance" does the tip of the cone move in half a period?

The position of the system at the beginning of the half-period is .  The position of the system at the end of the half-period is obtained by plugging in (a whole period is ).  .

The distance traveled during the half-period is the final period is .  It traveled 4cm.