Final answer:
Objects dropped or launched with only horizontal velocity from the same height will hit the ground simultaneously because gravity affects all objects equally, causing them to accelerate at the same rate vertically, regardless of their horizontal motion.
Step-by-step explanation:
If an object is dropped from rest and another object is launched horizontally from the same height, according to the principles of physics, they will hit the ground at the same time, assuming there is no air resistance. This is because the horizontal motion does not affect the vertical acceleration due to gravity, which is 9.8 m/s2 downwards. An experiment could involve launching ball A horizontally, dropping ball B from rest, and launching ball C vertically, all from the same elevation of 1.5 meters. To test the hypothesis that acceleration is independent of the object's velocity, the student would need to collect data on the time it takes for each ball to reach the ground. They should observe that despite having initial velocities in various directions, all balls experience the same vertical acceleration and hence fall for the same duration.