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Always considered antimater as negative mass so: $$m1=10kg(matter)$$ $$m2=-10kg(antimater)$$ $$displacement=r=10m$$ $$gravity =\frac{Gm1m2}{r^2}=-1N<0!HOW?$$

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  • Physicists mostly expect antimatter to have positive gravitational mass because it has positive inertial mass, but until that's empirically verified it's the subject of a small controversy.
  • The sign of a force indicates whether it attracts or repels. (If any inertial mass were negative, you'd have to take that into account as well.
  • In fact, Newton's formula for the gravity between two positive gravitational masses reflects its being attractive by having a minus sign you didn't know about, in $-Gm_1m_2\vec{r}/r^2=-Gm_1m_2\hat{r}/r^3$.
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  • $\begingroup$ By assuming antimater mass <0 I felt it would repel mater. $\endgroup$ – ask Nov 25 '20 at 6:50
  • $\begingroup$ @ask Well, now I've explained how signs work, you needn't ever get confused when doing these calculations. $\endgroup$ – J.G. Nov 25 '20 at 7:14

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