Two particles are executing simple harmonic motion. At an instant of time t, their displacements ay1= A cos (ωt) and y2 = A sin (ωt) Then, the phase difference between y1 and y2 is
120°
90°
180°
zero
y1=A cos ωt=A sin ωt+π2
y2=A sin ωt
∴ Δϕ=ωt+π2-ωt=π2=90°