posted by winterWX .
A solid uniform sphere has a mass of 2.0 104 kg and a radius of 1.5 m. What is the magnitude of the gravitational force due to the sphere on a particle of mass m = 0.2 kg located at a distance of 1.6 m from the center of the sphere? What if it is 1.1 m from the center of the sphere?
Use the universal law of gravity
F = G M m /R^2,
where G is the universal gravitational constant and R is the separation distance between the center of the sphere and the particle. M amd m are the masses of the sphere and the particle, respectively. Consider the "particle" to be a point source.
In the first case, R = 1.6 m. In the second case, the particle is inside the sphere, and only the mass of the larger sphere that is inside r = 1.1 m contributes a net gravitational attraction. For that case, use M = 2.0*10^4 * (1.1/1.5)^3, since that is the mass inside r = 1.1 m.
Ok thanks a lot!!!