Shell theorem: Difference between revisions

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m Fixing broken anchor: 2011-02-01 (VERY DIFFERENT 44≥17) #Vector components⇝Euclidean vector#Decomposition
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Applying [[Newton's Universal Law of Gravitation]], the sum of the forces due to the mass elements in the shaded band is
:<math>dF = \frac{Gm}{s^2} dM.</math>
However, since there is partial cancellation due to the [[Euclidean vector|vector]] nature of the force in conjunction with the circular band's symmetry, the leftover [[Vector (geometry)#Vector componentsDecomposition|component]] (in the direction pointing towards {{nowrap|<math>m</math>)}} is given by
:<math>dF_r = \frac{Gm}{s^2} \cos(\varphi) \, dM</math>
The total force on {{nowrap|<math>m</math>,}} then, is simply the sum of the force exerted by all the bands. By shrinking the width of each band, and increasing the number of bands, the sum becomes an integral expression: