Equation for Newton’s universal law of gravitation for radius 0

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Curiosity Science Physics Equation for Newton’s universal law of gravitation for radius 0

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  • In deep space imagine taking a ring with a radius of r. Then taking a ball that would fit in the ring with a radius of a (a < r).

    By fitting the ball perfectly in the ring we align the centre of gravity in the ball and in the ring. Now both centres of gravity’s are at the same point. Now we put Newton’s law of universal gravitation which is F=G(m1.m2)/r^2.

    But we know that r=0 so the force would be infinity (we haven’t figured out how to divide by 0 but it would be very high). But we can remove the ball from the ring easily. The question is why?

    – Asked by Chs via the ask a science question page.

  • Newton’s gravitational law is applied for point masses only. So when you assume two-point masses overlapping one another, the r is 0. But that’s just the mathematical expression going to infinity. In reality, it is impossible due to Pauli exclusion principle. You cannot have two masses occupying the same position.

    For your example, take a look at Shell Theorem.

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