Iceland has both high geothermal activity, with high temperatures near the surface, and abundant cold surface water. Iceland has many power plants that take advantage of the proximity of these natural hot and cold reservoirs. One plant uses an underground source at 122°C as the hot reservoir and a nearby lake at 5°C as the cold reservoir. The plant draws 16 MW from the hot reservoir to produce 1.8 MW of electricity. How does the actual efficiency ofthe plant compare to the theoretical maximum efficiency?

The metabolic power for typing is 150 W for Lili, not a lot as you know probably. How long does it take to burn off the energy in a slice of apple pie, which energy content is 1680 kJ (400 food calorie), in minutes?  (Try to stay active, working/studying in front of a computer is not the best exercise you can do for your body.) Your answer needs to have 3 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement.

As a gasoline engine is running, the amount of gasoline containing 15,000J of chemical potential energy is burned in 1 s. During that second, the engine does 3,000J of work. The burning gasoline has a temperature of about 2500 K. The waste heat from the engine flows into the air at about 300 K. What is the Carnot efficiency of a heat engine operating between these two temperatures?

In Arizona, photovoltaic (PV) panels can generate an average annual power of 1 MW/acre. If there are 311 sunny days per year in Arizona, but only 160 sunny days per year in Pennsylvania, how much average power (in MW/acre) could the same PV panels generate in Pennsylvania? Please include two decimal places in your answer. Note: assume that a cloudy day delivers 0 watts/acre of solar power. This is not true, but it simplifies the problem for us.

4. Suppose that a nuclear power plant has an efficiency of about 0.34, and generates 1000 MW of power. It is located on the banks of a major river that is 67 m wide near the plant, approximately 3 m deep, and flows at a rate of 0.5 m/s. Suppose that the plant re-routes all of this water into the plant and dumps its waste heat evenly throughout the water, then returns the warmer water to the river. How much warmer is the river downstream of the plant compared to upstream? Water's specific heat is approximately 4184 J/kg/K, and its density is 1000 kg/m³. [Answer: The water is warmer by 4.62 K. This is a lot warmer!]

Iceland has both high geothermal activity, with high temperatures near the surface, and abundant cold surface water. Iceland has many power plants that take advantage of the proximity of these natural hot and cold reservoirs. One plant uses an underground source at 122°C as the hot reservoir and a nearby lake at 5°C as the cold reservoir. The plant draws 16 MW from the hot reservoir to produce 1.8 MW of electricity. How does the actual efficiency of the plant compare to the theoretical maximum efficiency?

Question 6. in one cycle, a heat engine does 700J of work and releases 1450 J of heat to a lower-temperature reservoir. What is the efficiency of this engine, in percent?

A bathroom extractor fan being sold on Amazon has a duct diameter of 10.0 cm. It extracts air from a bathroom at a rate of 70.0 m3/h and the power supplied to the fan is 7.0 W. With what efficiency does the extractor convert electrical power into the kinetic power associated with the air-motion? Take the density of air to be 1.2 kg/m3 and assume laminar air flow.