Even though we don’t feel the gravity but is it true that we also attract every other object on the planet along with the earth attracting us.
Can I say that a human also has gravity?
Can we find our gravity attraction range.
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3$\begingroup$ Related question: What is the smallest item for which gravity has been recorded or observed? $\endgroup$– BioPhysicistCommented Dec 11, 2020 at 15:03
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3 Answers
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Every object in this universe attracts every other object; this force is gravitational force. The magnitude of force that we exert on an object and the object exerts on us is equal.
Can I say that a human also has gravity ?
A better statement will be that humans have a gravitational field.
Even though we don’t feel the gravity but is it true that we also attract every other object on the planet + the earth attracting us
$F_g=\dfrac{GM_1M_2}{R^2}$ here is the expression for force you can see that the magnitude of force on earth and on us is same. It is just that effect of this force is different
$$a_{\text{humans}}=\frac{F}{m_{\text{humans}}}$$ $$a_{\text{earth}}=\frac{F}{m_{\text{earth}}}$$
As the mass of earth is far more than that of a human, the acceleration of earth is almost negligible.
For calculating range, you can see that it is operative only at small distances, as it is inversely proportional to square of distance.
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The earth attracts you, and you also attract it, but due to the earth's huge mass resulting in its huge inertia, it doesn't move noticeably, but you do.
The force of gravity is given by formula:
$$F=G * \frac{m_1*m_2}{r^2}$$
Where $m_1$ and $m_2$ are masses of the two bodies, $r$ is the distance of separation between them.
Hence, You attract every other object in the universe too (except when $r$ is infinity, the force is zero).
However, either due to huge value of $r$ or huge mass of the body you are attracting, you don't see a result.
The value of $G$ is numerically $6.67 * 10^{-11}\ \mathrm{N\, m^2\, kg^{-2}}$.
Suppose two bodies of masses $1\ \mathrm{kg}$ each kept at separation of $1\ \mathrm{m}$.
Hence,
\begin{align} F &= 6.67 * 10^{-11}* \dfrac{1 * 1}{1^{2}}\\ &= 6.67 * 10^{-11}\ \mathrm{N} \end{align}
Hence, it's a very small force and you don't experience it.
But if we consider masses of the earth and moon and workout the same thing, the force is $F = 2*10^{20}\ \mathrm{N}$ This is why the moon revolves around the earth.
Hence, the force is quite large between bodies of huge mass.
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Yes, every massive object attracts any object with mass in Newtonian mechanics (in a general relativistic view it would actually be: every object with energy is a source of curvature of the spacetime). In Newtonian mechanics, the gravitational force has an infinite range (and it is an instantaneous force), but the intensity decreases with the distance:
$$\vec{F}_g= G \frac{M m}{r^2}\hat{r}$$
The value of the force on an object with mass $m$ depends on the $M$, the mass of the object that is attracting it, and on the inverse of the distance $r$. So the further away you are the less attracted you feel but the force is actually zero only for $r \rightarrow \infty$.
