Answer:
[tex]F_g=461lb_f[/tex]
Explanation:
First calculate the mass of the asteroid. To do so, you need to find the volume and know the density of iron.
If r = d/2 = 645ft, then:
[tex]V = \frac{4}{3} \pi r^3[/tex]
[tex]V = 1.124*10^{9}ft^3[/tex]
So
[tex]\delta_{iron}=m/V=491lb/ft^3[/tex]
[tex]m=V*\delta=5.519*10^{11}lb[/tex]
Once you know both masses, you can calculate the force using Newton's universal law of gravitation:
[tex]F_g=G\frac{m_1m_2}{d^2}[/tex]
Where G is the gravitational constant:
[tex]G= 1.068846 * 10^{-9} ft^3 lb^{-1} s^{-2}[/tex]
[tex]F_g=461lb_f[/tex]