Identical isolated conducting spheres 1 and 2 have equal charges and are separated by a distance that is large compared with their diameters. the magnitude of the electrostatic force acting on sphere 2 due to sphere 1 is f = 0.42 n. suppose now that a third identical sphere 3, having an insulating handle and initially neutral, is touched first to sphere , then to sphere 2, and finally removed. what is the magnitude of the electrostatic force f' that now acts on sphere 2?

Na food processing facility, a spherical container of inner radius r1 5 40 cm, outer radius r2 5 41 cm, and ther- mal conductivity k 5 1.5 w/m · k is used to store hot water and to keep it at 100°c at all times. to accomplish this, the outer surface of the container is wrapped with a 800-w electric strip heater and then insulated. the temperature of the inner surface of the container is observed to be nearly 120°c at all times. as- suming 10 percent of the heat generated in the heater is lost through the insulation, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the container, (b) obtain a relation for the variation of temperature in the container material by solving the differential equation, and (c) evaluate the outer surface tempera- ture of the container. also determine how much water at 100°c this tank can supply steadily if the cold water enters at 20°c.

Aray of light traveling parallel to the principal axis of a concave mirror will be reflected through the mirror's

If the radius of curvature of the cornea is 0.75 cm when the eye is focusing on an object 36.0 cm from the cornea vertex and the indexes of refraction are as described before, what is the distance from the cornea vertex to the retina? express your answer to two significant