Both you and the article are right - you are analyzing it in the frame of reference where the center of the earth is stationary, while the article analyzes in the frame of motion where the center of the rocket is stationary.<p>Since the frame where the center of the rocket is stationary is a non-inertial frame, Newton&#x27;s law doesn&#x27;t apply [1]. However a modification of Newton&#x27;s law that includes a so-called &quot;ficticious force&quot; applies [2] (I don&#x27;t think this modification has a name). This is why the article says there&#x27;s an outward acceleration, because in the frame where the center of the rocket is stationary, the outward acceleration is caused by the ficticious force.<p>[1]: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Newton%27s_laws_of_motion" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Newton%27s_laws_of_motion</a> begins the laws with &quot;when viewed in an inertial reference frame&quot;<p>[2]: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Non-inertial_reference_frame" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Non-inertial_reference_frame</a> quotes, &quot;One might say that F = ma holds in any coordinate system provided the term &#x27;force&#x27; is redefined to include the so-called &#x27;reversed effective forces&#x27; or &#x27;inertia forces&#x27;.&quot;