Suppose the field inside a large piece of magnetic material is b0, so that h0 = (1/μ0)b0 − m, where m is a "frozen-in" magnetization. (a) now a small spherical cavity is hollowed out of the material (fig. 6.21). find the field at the center of the cavity, in terms of b0 and m. also find h at the center of the cavity, in terms of h0 and m. (b) do the same for a long needle-shaped cavity running parallel to m. (c) do the same for a thin wafer-shaped cavity perpendicular to m.

Arock can be broken down into different kinds of substances by physical processes. no chemical reactions are needed to separate different parts of a rock into pure substances. this is because a rock is a(n)

Achemical reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. an example of a chemical reaction is the formation of water from hydrogen and oxygen gas. in a physical change, a substance changes its physical appearance but not its chemical identity. an example of physical change is the formation of liquid water from solid water, a familiar process called melting. physically, liquid water looks very different from solid water (ice) but the chemical identity, water, is the same for both. which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions? oxygen gas changes to ozone during thunderstorms carbon dioxide is produced by the combustion of gasoline in an automobile engine. when coal, oil, and natural gas are decomposed in landsills they produce methane gas. freezing rain develops when a warm air mass overrides a cold air mass. fog forms from water vapor when the temperature drops below the dew point

Which of the following would have less momentum than a 52 kg cheetah running at 10 m/s?