At t=0s a block attached to a horizontal spring has a displacement of +0.18m and is moving toward the equilibrium position. The block first passes through x=0m at t=0.19s and returns to +0.18m at t=0.50s. Its motion can be modeled by x=Acos(ωt+φ). Which of the following is the best value for the phase constant φ?
a) 0rad
b) +1.57rad
c) +0.79rad
d) −0.79rad