In the equation V = at, the right side represents the change in velocity (ΔV) over time (t), where a is the acceleration. The left side of the equation represents the final velocity (V).
When the initial velocity (Vi) is zero, the equation simplifies to V = at, because the initial velocity term is zero. In this case, we are considering the scenario where the object starts from rest (zero initial velocity) and accelerates at a constant rate (a) over time (t).
The equation V = at is derived from the equation V = Vi + at, where Vi is the initial velocity. When Vi is zero, the equation reduces to V = at.
It's important to note that this equation is applicable only when the acceleration is constant. In the case of a ball thrown vertically upwards, the acceleration changes due to the influence of gravity. In such cases, we need to consider the appropriate equations of motion that account for changing acceleration, such as the kinematic equations of motion or equations derived from Newton's laws of motion.