Final answer:
Both the tennis ball and the solid steel ball will have the same acceleration when dropped at the same time, neglecting air resistance.
Step-by-step explanation:
In this scenario, both the tennis ball and the solid steel ball have the same diameter and are dropped at the same time. Assuming we ignore air resistance effects, both objects experience the acceleration due to gravity.
According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Since both balls have the same diameter, their masses can be considered the same, so the acceleration experienced by both balls will be equal.
Therefore, both the tennis ball and the solid steel ball will have the same acceleration when dropped at the same time, neglecting air resistance.