When earth and the moon are separated by a
distance of 3.84 × 10^8 meters, the magnitude of
the gravitational force of attraction between
them is 2.0 × 10^20 newtons. what would be the
magnitude of this gravitational force of attraction
if earth and the moon were separated by a
distance of 1.92 × 10^8 meters?
(1) 5.0 × 10^19 n (3) 4.0 × 10^20 n
(2) 2.0 × 10^20 n (4) 8.0 × 10^20 n

Consider a uniformly charged ring in the xy plane, centered at the origin. the ring has radius a and positive charge qdistributed evenly along its circumference. a)what is the direction of the electric field at any point on the z axis? . b)what is the magnitude of the electric field along the positive z axis? use k in your answer, where k=14πϵ0. d)the ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. what will be the angular frequency ω of these oscillations? use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. express your answer in terms of given charges, dimensions, and constants