Some charged particles are suspended inside a hollow metal object by supports made of a material that is an electrical insulator. The metal object has charge +q distributed over its outer surface and charge ?2q distributed over its inner surface. A. How much charge is suspended in the cavity?

B. What is the charge on the object? (Hint: What is the electric field a very large distance r from the center of the object?)

What are the applications of electromagnetic waves

Which diagram correctly demonstrates the various forces acting on a ball moving horizontally with some speed?

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.