Projectile Motion Explaination (1 Viewer)

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Two spheres are launched horizontally from a 1.0m high table. Sphere A has a mass of 1.0kg and is launched with an initial speed of 5.0 m/s. Sphere B has a mass B has a mass of 0.4kg and is launched with an inital speed of 2.5 m/s.

Compare the times for each sphere to hit the floor.
Compare the distances that each travels from the edge of the table.

I just need some explaination in the concept of the first question.
I know the the equation used to find the time is [tex] t = \sqrt{ \frac {2h}{g}} [/tex] and the answer is 0.45s
But I don't understand why the different masses and velocities don't have an effect on the time to fall.
the same reason that if you fire a bullet horizontally and drop one at the same instant they will hit the ground at the same instant
The initial velocity is perpendicular to the acceleration and has no effect on it, and the acceleration of gravity is independant of mass

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