Hey guys, So I was trying to do a few questions to prepare for my Differential Equations exam soon, and I stumbled upon this question: A mass of 1 slug is suspended from a spring whose spring constant is 9lb/ft. The mass is initially released from a point 1 foot above the equilibrium position with an upward velocity of square root 3 ft/s. Find the times at which the mass is heading downward at a velocity of 3 ft/s. What I did was I took downward as positive while downward as negative. But I only managed to get 1 value for t, which is 0.6s. My equation for the motion was x(t)= -cos 3t - (square root 3/ 3) sin 3t Please help me...Thanks !