When two point charges are a distance d apart, the magnitude of the electrostatic force between them is f. if the distance between the point charges is increased to 3d, the magnitude of the electrostatic force between the two charges will be

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this