Aparallel-plate capacitor having circular plates of diameter d and a distance d apart stores energy u when it is connected across a fixed potential difference. if you want to triple the amount of energy stored in this capacitor by changing only the size of its plates, the diameter should be changed to:

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.