[填空题]
The Near Earth Asteroid Rendezvour6n n0t* z*uers (NEAR), after traveling 2.1 billion km, ijrjet3oj); t 77o-fly0mbh;ts meant to 7 -;tj bojylo3fh7)t m0re; jtorbit the asteroid Eros at a height of about 15 km . Eros is roughly 40 $\mathrm{~km} \times 6 \mathrm{~km} \times 6 \mathrm{~km}$ . Assume Eros has a density (mass/volume) of about 2.3 $\times 10^{3} \mathrm{~kg} / \mathrm{m}^{3}$ . (a) What will be the period of NEAR as it orbits Eros? $\approx$ $\times 10^4$sec
(b) If Eros were a sphere with the same mass and density, what would its radius be? $\approx$ $\times 10^3$
(c) What would g be at the surface of this spherical Eros?$\approx$ $\times 10^{-3}$
