You have an arbitrary distribution of negative charge contained within a sphere of radius RR. Describe the electric field at a distance 100R100 R from the charge distribution. 1/(100)^2 =10^-4 Now choose from one of the following optionsWhy? a The field will be in the direction normal to the charge distribution. b The field will be in the direction tangential to the charge distribution. c The field will be zero at this position. d The field will be infinite at this position. Submit

Spend time observing or thinking about events that involve matter and energy. which events can you explain? which events can’t you explain?

Aheat engine running backward is called a refrigerator if its purpose is to extract heat from a cold reservoir. the same engine running backward is called a heat pump if its purpose is to exhaust warm air into the hot reservoir. heat pumps are widely used for home heating. you can think of a heat pump as a refrigerator that is cooling the already cold outdoors and, with its exhaust heat qh, warming the indoors. perhaps this seems a little silly, but consider the following. electricity can be directly used to heat a home by passing an electric current through a heating coil. this is a direct, 100% conversion of work to heat. that is, 19.0 \rm kw of electric power (generated by doing work at the rate 19.0 kj/s at the power plant) produces heat energy inside the home at a rate of 19.0 kj/s. suppose that the neighbor's home has a heat pump with a coefficient of performance of 4.00, a realistic value. note: with a refrigerator, "what you get" is heat removed. but with a heat pump, "what you get" is heat delivered. so the coefficient of performance of a heat pump is k=qh/win. an average price for electricity is about 40 mj per dollar. a furnace or heat pump will run typically 200 hours per month during the winter. what does one month's heating cost in the home with a 16.0 kw electric heater? what does one month's heating cost in the home of a neighbor who uses a heat pump to provide the same amount of heating?

The heliocentric and the geocentric models of the solar system included these central principles