# Physics

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In Larry Niven’s science fiction novel
Ringworld, a ring of material of radius
1.54 × 1011 m rotates about a star with a ro-
tational speed of 1.38 × 106 m/s. The inhab-
itants of this ring world experience a normal
contact force ~n. Acting alone, this normal
force would produce an inward acceleration of
9.28 m/s2. Additionally, the star at the cen-
ter of the ring exerts a gravitational force on
the ring and its inhabitants.

The difference between the total acceleration
and the acceleration provided by the normal
force is due to the gravitational attraction of
the central star.
Find the approximate mass of the star.

• Physics -

**** u guys

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