1. The problem statement, all variables and given/known data http://i.imgur.com/u8vUv5a.jpg Find the phase constant. 2. Relevant equations x(t)=Acos(ωt + Φ) v(t)=-Aωsin(ωt + Φ) Vmax = ωA ω=2π/T 3. The attempt at a solution ω = 2π/12 = 0.5236 A = 60/0.5236 = 114.59 cm v(0) = -30 = -114.59(0.5236)sinΦ 0.5 = sinΦ Φ = π/6 and 5π/6. Which angle is correct?