9. when considering a magnet's force of attraction over a known distance, you would expect the strength of attraction 4 inches away from the magnet to be weaker than the strength of attraction at 1 inch from the magnet.
a. 6 times
b. 16 times
c. 4 times
d. 8 times

Space vehicles traveling through earth's radiation belts can intercept a significant number of electrons. the resulting charge buildup can damage electronic components and disrupt operations. suppose a spherical metallic satellite 1.3 m in diameter accumulates 3.0 µc of charge in one orbital revolution. (a) find the resulting surface charge density. (b) calculate the magnitude of the electric field just outside the surface of the satellite, due to the surface charge.

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.

A51 kg woman skis down a hill and her kinetic energy is 9.96e4 j. what is her speed?