Astronomy Practice Exam 2026 – Complete Preparation Guide

Galileo's response to the objection that moving objects in air would fall behind a moving Earth is rooted in his understanding of inertia and relative motion. He argued that if the Earth were moving, the air surrounding it would also be moving along with it. This means that objects in the air would not be left behind because both the objects and the air are moving at the same velocity as the Earth.

By demonstrating that objects in air remain in motion, he highlighted the concept of inertia, asserting that a moving object will continue in its state of motion unless acted upon by an external force. Thus, in a moving system such as the Earth, the air and objects within it would not experience any noticeable discrepancy in motion relative to the Earth’s movement. This was a fundamental step in understanding motion and laid the groundwork for later advancements in physics.

The other options do not accurately encapsulate Galileo's reasoning or the scientific principles at play regarding motion, inertia, and the influence of surrounding mediums like air.