The two equations where the initial velocity (u) is featured require time (T) to be determined. In this experiment, the time taken for the projectile of the ball to complete a distance is not taken and therefore, we cannot use Newton’s to calculate the initial velocity.
According to the law of energy conservation, the energy content of a body cannot be lost. In this case, the energy content at the beginning of the projectile motion will be the same at all stages. This means that the total kinetic energy at the beginning will be converted to potential energy at the highest point. That