<span>In Coulomb's law, however, the
magnitude and sign of the electric force are determined by the electric
charge, rather than the mass, of an object. ... Thus, two negative
charges repel one another, while a positive charge attracts a negative
charge. The attraction or repulsion acts along the line between the two charges</span>
This is called refraction. Some common examples of refraction are a straw appearing bent or cut once it enters water in a glass.
The reaction time of Boris is t(r), so before that, Boris will not have jumped. Thus, H(b)(t) = 0
The vertical displacement will simply be
D(t) = H(a)(t)
Answer: object B is negatively charged, object C is positively charged and object D is also positively charged
Explanation: since unlike charges attract and like charges repel, for object A which is positively charged and B to attract B must be negatively charged and then for B which is negatively charged and C to attract C must be positively charged and for C and D to repel they have to be of thesame charge which means D is positive as well.