I am currently studying collisions from an online lecture and the teacher in it says that both perfectly elastic and perfectly inelastic collision are practically not possible.
I am able to find the reason why elastic collisions are practically impossible that is because there is always some loss of kinetic energy of system as heat (due to friction ), sound etc.
But I cannot figure out why perfectly inelastic collision are not possible.
I think perfectly inelastic collisions are possible for example if we take a vacuum chamber and inside it place two identical modelling clay balls tied to identical strings and held at same angle as shown in figure. Then we release the clay ball simultaneously and they hit each other and stop at the middle then it will be a perfectly inelastic collision.
Is there any fallacy in my statement or the statement of the teacher ?