Out of the following functions representing motion of a particle which represents SHM(I) y = sin ωt - cos ωt(II) y = sin3ωt(III) y = 5 cos(3π4-3 ωt)(IV) y = 1+ωt + ω2t2

For a simple harmonic motion d2ydt2 ∝ -yHence, equation y = sin ωt - cos ωt  andy = 5 cos (3π4-3ωt) satisfy this condition and equation y = 1+ωt+ω2t2 is not periodic and y = sin3ωt is periodic but not SHM.