Two point charges, q1 and q2, are separated by a distance r. if the magnitudes of both charges are halved and their separation is also halved, what happens to the electrical force that each charge exerts on the other one?

a.) it increases by a factor of 8.
b.) it remains the same.
c.) it increases by a factor of 2.
d.) it increases by a factor of 16.
e.) it increases by a factor of 4.

A5 foot by 5 foot box culvert is buried 6 feet beneath the surface of the ground. a crosssection of this very long culvert (into and out of the page) is illustrated below. assume that the soil in which the culvert is buried has the following properties: jt = 120 pcf, w = 12%, ko = 0.50, ka = 0.33, and kp = 3.00. calculate the total horizontal force per unit length of culvert (fh) felt on one of the vertical faces of the culvert.