Question

which piece of text uses this meaning of gravity?
gravity noun the physical force of attraction
published in 1687, sir isaac newtons philosophiae naturalis principia mathematica (mathematical principles of natural philosophy) outlined three basic laws of physics and explained how gravity keeps the planets in orbit.
brenda failed to reveal the gravity of the situation when she told me the news of her brothers illness.

Explanation:

The defined meaning of "gravity" is the physical force of attraction. The first text references Newton's work explaining how this physical force keeps planets in orbit, which matches the given definition. The second text uses "gravity" to mean seriousness of a situation, not the physical force.

Answer:

Published in 1687, Sir Isaac Newton's Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) outlined three basic laws of physics and explained how gravity keeps the planets in orbit.