A solid uniform sphere has a mass of 7.0 104 kg and a radius of 1.2 m.

(a) What is the magnitude of the gravitational force due to the sphere on a particle of mass m = 0.7 kg located at a distance of 2.1 m from the center of the sphere?
N
(b) What if it is 1.0 m from the center of the sphere?
N

3 answers

I will gladly help the first student who shows evidence of his or her own work. You do not appear to be among that vanishing group.
Okay so far i have F=Gm1m2/r^2
G=6.67 x10^-11
m1=.7
m2=7.0x10^4
what do i use for r?
a. f=(G*m1*m2)/r^2
=(6.67x10^-11*.7*70000)/2.1^2)
=7.4*10^-7 N
b. f=(G*m1*m2)/r^2
=(6.67*10^-11*.7*70000)/1^2
=3.29*10^-6