We consider a simple collinear collision ofa "classical" particle with a harmonic oscillator within quantum semiclassical model and full quantum dynamics model, in which the latter is solved analytically in squeezed state and exact diagonalization methods and acts as the exact solution of such a system. A comparison of these two models for different mass ratios between the "classical" particle and the quantum particle is done, which gives a criterion when using the quantum-semiclassical model.