Which Of The Following Objects Exerts A Gravitational Force

You're sitting in a coffee shop. And your phone sits on the table. None of them are drifting toward each other in any obvious way. The ceramic mug warms your hands. On top of that, none of these things are floating away. The person three tables over laughs at something on their laptop. But every single one of them — the phone, the mug, the person, the table, the building, the Earth beneath it all — is pulling on every other one right now.

The question "which of the following objects exerts a gravitational force" shows up in physics textbooks, multiple-choice exams, and late-night Google searches. The answer is simpler than most people expect, and stranger than most people realize.

What Is Gravitational Force

Gravity isn't a force that only planets and stars have. Consider this: it's not something that "turns on" at a certain size threshold. Now, gravity is a fundamental interaction that exists between any two objects with mass. Full stop.

Your coffee mug pulls on the Earth. The Earth pulls on your coffee mug. That's why the pull is mutual, equal in magnitude, opposite in direction — Newton's third law in its purest form. The reason you don't see the mug leap toward you or the Earth lurch toward the mug comes down to mass. On the flip side, the Earth masses about 5. 97 × 10^24 kilograms. Your mug masses maybe 0.That's why 3 kilograms. The acceleration each experiences from that mutual pull differs by a factor of roughly 10^25.

The Mass Requirement

Here's the rule: if it has mass, it exerts gravitational force. A neutrino (which has a tiny, non-zero mass) pulls on a galaxy cluster. That's it. No special composition required. Think about it: no minimum mass. A hydrogen atom pulls on another hydrogen atom. The force scales with the product of the two masses and drops with the square of the distance between their centers of mass.

This means the answer to "which of the following objects exerts a gravitational force" is always: all of them. Every single option on that multiple-choice list. This leads to the feather. So the rock. Plus, the photon — wait, photons are massless. But they carry energy, and in general relativity, energy curves spacetime too. The bowling ball. We'll come back to that.

Mass vs. Weight

People confuse these constantly. Consider this: your mass is the same on Earth, on the Moon, and in deep space. Weight is the force gravity exerts on that mass in a particular gravitational field. Mass is the amount of matter in an object — its resistance to acceleration, its "heft" in a deep, inertial sense. Your weight changes drastically.

An object in orbit isn't weightless because gravity stopped pulling. It's weightless because it's in free fall, moving forward fast enough that its fall curves around the planet instead of into it. The gravitational force at the International Space Station's altitude is still about 90% of what it is on the surface. The astronauts and the station and the Tang packets are all falling together.

Why It Matters

Understanding that everything* with mass pulls on everything* else changes how you see the world. It's not just a textbook fact — it's the reason the universe has structure at all.

Structure Formation

Right after the Big Bang, matter was distributed almost perfectly evenly. Almost. Tiny quantum fluctuations left some regions slightly denser than others. Those slightly denser regions pulled a little harder on their surroundings. Over billions of years, that tiny extra pull gathered gas into clouds, clouds into stars, stars into galaxies, galaxies into clusters and superclusters and the cosmic web we see today.

Without universal mutual attraction, the universe would be a thin, cooling gas. On top of that, no stars. No planets. No coffee shops.

Everyday Consequences

Closer to home, the fact that your body exerts gravitational force has measurable effects. Worth adding: cavendish measured it in 1798 using lead spheres and a torsion balance — the first laboratory measurement of the gravitational constant G. Modern versions of the experiment can detect the gravitational pull of a person walking past the apparatus.

Your body pulls on the person next to you on the subway. The pull is absurdly small — on the order of micronewtons at arm's length — but it's not zero. It's never zero.

Tides

The Moon pulls on Earth's oceans. Now, the Sun pulls too, about 46% as strongly as the Moon despite being vastly more massive, because it's so much farther away. The differential pull — stronger on the near side, weaker on the far side — stretches the oceans into tidal bulges. This leads to earth rotates under those bulges. High tide, low tide, repeat.

But the Moon also pulls on the solid Earth. The ground rises and falls by up to 30 centimeters twice a day. You've never noticed it because everything around you rises and falls together. The effect is real, though, and it's slowly lengthening Earth's day and pushing the Moon outward.

How It Works

Newton gave us the equation. Einstein gave us the deeper picture. Both are useful depending on what you're trying to do.

Newton's Law of Universal Gravitation

F = G(m₁m₂)/r²

Continue exploring with our guides on when light enters a medium from space it and how to find grams of an element in a compound.

Force equals the gravitational constant times the product of the two masses divided by the square of the distance between their centers. Practically speaking, 674 × 10⁻¹¹ N·m²/kg². G ≈ 6.That tiny constant is why gravity feels so weak compared to electromagnetism — a fridge magnet beats the entire Earth's pull on a paperclip.

The inverse-square part matters enormously. Which means double the distance, quarter the force. Halve the distance, quadruple the force. This is why tides depend on distance more than mass — the Moon's proximity beats the Sun's mass.

Center of Mass

For spherical objects (or objects far enough away to approximate as spheres), you can treat all the mass as concentrated at the center. In real terms, the Earth isn't a perfect sphere — it bulges at the equator, has mountains and trenches and density variations. But for irregular shapes up close, you have to integrate the pull from each mass element. This simplifies calculations enormously. Satellites in low orbit feel these irregularities as tiny perturbations in their trajectories.

If you take away one thing from this section, make it this.

General Relativity

Einstein reframed gravity not as a force but as curvature of spacetime. Mass tells spacetime how to curve; curved spacetime tells mass how to move. A planet orbiting a star isn't being "pulled" — it's following a geodesic, the straightest possible path through curved geometry.

This matters in extreme conditions: near black holes, for GPS satellite timing (relativistic corrections are essential for accuracy), for the precession of Mercury's orbit. For dropping a coffee mug, Newton works fine.

The Photon Question

Photons have zero rest mass. But photons carry energy (E = hf) and momentum. In Newton's framework, zero mass means zero gravitational force. In real terms, in general relativity, the stress-energy tensor — not just mass — sources spacetime curvature. Light bends around massive objects. This was confirmed during the 1919 solar eclipse and is now routine in gravitational lensing observations.

So photons do participate in gravity, just not via the Newtonian mass term. They also generate* gravity — a box of light weighs more than an empty box. The energy inside contributes to the system's total mass-energy.

Common Mistakes

"Only Big Things Have Gravity"

This is the big one. People hear "gravity" and think "planets." But the gravitational constant G is universal. It applies to everything. In real terms, the force between two 1-kg masses 1 meter apart is 6. 674 × 10⁻¹¹ newtons — tiny, but nonzero. Sensitive torsion balances measure it routinely.

"Gravity Stops at

the edge of the atmosphere"

This is a common misconception fueled by the term "zero gravity" used to describe astronauts on the International Space Station. Plus, the reason astronauts float isn't because gravity has vanished, but because they are in a state of perpetual freefall. That's why in reality, gravity doesn't have a boundary. Here's the thing — they are moving sideways fast enough that as they fall toward Earth, the surface curves away beneath them. Here's the thing — at the altitude of the ISS, Earth's gravity is still roughly 90% as strong as it is on the surface. They aren't weightless; they are simply in orbit.

"Weight and Mass are the Same"

In casual conversation, we use these interchangeably, but in physics, they are distinct. And weight is a force—the result of gravity acting on that mass, measured in Newtons. Because of that, mass is an intrinsic property—the amount of matter in an object, measured in kilograms. If you travel to Mars, your mass remains identical, but your weight drops to about 38% of its Earth value because the Martian gravitational field is weaker.

The Great Unification

Despite its ubiquity, gravity remains the "odd one out" in modern physics. We have the Standard Model, which beautifully explains electromagnetism and the strong and weak nuclear forces via particle exchange. Gravity, however, refuses to be quantized.

The hypothetical "graviton"—the particle that would carry the gravitational force—has never been detected. When we try to apply quantum mechanics to general relativity, the math breaks down, producing "infinities" that make no physical sense. This is the central conflict of theoretical physics: the very large (General Relativity) and the very small (Quantum Mechanics) speak different languages.

Conclusion

From the simple fall of an apple to the collision of supermassive black holes, gravity is the architect of the universe. It governs the lifecycle of stars, the rotation of galaxies, and the ticking of our clocks. Also, while Newton gave us the tools to handle the solar system and Einstein gave us the keys to understand the cosmos, the full story of gravity remains unfinished. Whether the answer lies in String Theory, Loop Quantum Gravity, or a yet-undiscovered principle, the quest to unify gravity with the other forces of nature remains the "Holy Grail" of science—a journey to understand the fundamental fabric of existence itself.