(ii) a large electroscope is made with "leaves" that are 78-cm-long wires with tiny 21-g spheres at the ends. when charged, nearly all the charge resides on the spheres. if the wires each make a 26° angle with the vertical (fig. 16–55), what total charge q must have been applied to the electroscope?

Diamond will scratch quartz. true or false

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.

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?