1. The problem statement, all variables and given/known data A 225g mass attached to a horizontal spring oscillates at a frequency of 4.00 Hz. At t=0s, the mass is at x = 5.00 cm and has v_x = -37.0cm/s . Determine the phase constant. 2. Relevant equations velocity = v(t) v(t) = Aω·cos( ωt + ϕ ) 3. The attempt at a solution -37 cm/s = ( 5.2122*10^-2 m )( 25.133 rad/sec )cos( 0 + ϕ ) -0.282 = cos( ϕ ) ϕ = cos⁻¹( -0.282 ) ϕ = 106.40º = 1.857 radians ◄--- However that answer is wrong, and I am not sure why. Can anyone help?