A mass-spring system has an initial speed of 3 m/s in the negative x-direction and an initial position of 0.41 m. Calculate the phase shift in radians, assuming a cosine solution, with a spring constant of 499 N/m and a mass of 4 kg.

a) π/6 radians
b) π/4 radians
c) π/3 radians
d) 2π/3 radians