What is the principle of Physical Independence of Motions?

Principle of Physical Independence of Motions Motion of projectile is two-dimensional motion in a vertical plane. It can be resolved in two motions along horizontal vertical direction These two motions are independent of each other. This is called the principle of physical independence of motions. At any instant velocity of projectile has two components : (i) Horizontal Component : No acc. along horizontal $\left(\mathrm{a}_{\mathrm{x}}=0\right)$ so velocity along horizontal remains unchanged th...