Question 33949 General equation of harmonic motion is x=Acos(ωt+δ). Cyclic frequency might be found knowing the period T: ω=T2π. Since there were 150 oscillations in 5min, period is T=2s and frequency is ω=42π=π. The amplitude is A=5 and initial phase is δ=4π. Hence, the equation of motion is x=5cos(πt+4π). Maximum velocity is vmax=ωA=5π.