A mass hangs from the ceiling, held up by two springs in series. The upper spring has spring constant k1, and the bottom spring has spring constant k2. If the mass is displaced from equilibrium by a small amount x, it has a maximum speed v. If instead the mass is displaced by x/2, what is the maximum speed?
A. 41v
B. 21v
C. v
D. k1k2k1+k2v
E. k1k2k1−k2v
F. k1k2∣k1−k2∣v