Physics, 28.07.2019 19:30 natalie2sheffield

Is crumpling a sheet of paper a physical or chemical change? why?

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Physics, 22.06.2019 04:00

What is the scientific definition of energy that relates to work

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Physics, 22.06.2019 08:00

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?

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Physics, 23.06.2019 04:00

A15 ohm resistor and a 25 ohm resistor are connected in a series to a 60 volt battery. what is the power used by each device

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Physics, 23.06.2019 19:00

In september, lee ran in the run rabbit run 50 mile race in steamboat. the race is an out-and-back course, meaning that you start and run out from the base of steamboat ski resort up to rabbit ears, and then turn around and retrace your path to the finish. the table below provides the timed splits through the various aid stations along the course. time aid state (distance traveled from start) 0: 00: 00 start (0 miles) 1: 21: 51 mount werner aid station (6.4 miles) 2: 22: 52 long lake aid station (13.2 miles) 3: 34: 36 base camp trailhead aid station (18.4 miles) 4: 05: 34 dumont aid station (22.3 miles) 4: 45: 25 rabbit ears (25 miles) 5: 13: 17 dumont aid station (27.7 miles) 6: 02: 43 base camp trailhead aid station (31.6 miles) 7: 07: 11 long lake aid station (36.8 miles) 8: 41: 37 mount werner aid station (43.6 miles) 9: 29: 13 finish (50 miles) (a) explain if the table represents a function. if it does not, provide evidence supporting that it is not a function. if it is a function, describe the relationship between the independent variable and dependent variable in this scenario. (b) construct a graph that depicts the relationship between time and the total distance traveled in the race. (c) construct a graph that depicts the relationship between time and displacement from start/finish (relative distance to start/finish). (d) construct a graph that depicts the relationship between time and leeâ€™s speed running. (e) what can we infer about leeâ€™s speed at time 4: 05: 34? explain your reasoning.