The initial charges on the three identical metal spheres in the figure below are the following: sphere A, Q; sphere B,-Q/12; and sphere C, Q/6, where Q = 4.90 × 10-14 C. Spheres A and B are fixed in place, with a center-to-center separation of d = 3.7 m, which is much larger than the spheres. Sphere C is touched first to sphere A and then to sphere B and is then removed. What then is the magnitude of the electrostatic force between spheres A and B?

no

sodium is solid at rt

initial speed when it is dropped is 150 ft/s

now at the same moment the acceleration due to gravity is perpendicular to its velocity

so as we know that

now we have centripetal acceleration a = 32 ft/s^2 as its perpendicular to velocity

while tangential acceleration at the same moment will be zero

so

now radius of curvature is given as

so the radius of curvature just after it is dropped is 703.125 ft

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.