A light bulb has 75% efficiency. How much energy is wasted if the useful output energy of the bulb is 24 J? is the answer... a. 6.0 J b. 8.0 J c. 18 J d. 32 J e. 51J

For each of the following situations: a. Choose an initial and final state (states A and B) that will be appropriate (interesting) for analysis. b. If there is not already a physical diagram of the situation and there should be one for proper analysis, include one. c. Construct a system schema of the situation. Do not forget to include the system boundary for the system specified by the problem. Choose your system wisely. d. Construct an energy bar chart and system flow diagram (LOL plots) for each problem. e. You are allowed to add other energy storage modes. You do not have to use the energy storage modes that are printed in each LOL plot. f. Find the unknown value.

A girl pulls a 5kg wagon with a force of 20 n for 7 m. If the final speed of the wagon is 3.5 m/s, determine the efficiency of this process

A certain coal-fired power plant has a rated power capacity of P = 960 MW. The output of this plant is W = 0.39QH, where QH is the energy input as heat from the hot reservoir. a. Write an equation for the efficiency of a heat engine in terms of QH and the heat QC exhausted to a low-temperature reservoir.  b. Which would increase the efficiency more, doubling QH or reducing QC by half?  c. Calculate the maximum thermal efficiency of the power plant.  d.  Calculate the absolute value of the exhausted heat (QC) each second in MJ for the power plant.

A power plant has been proposed that would make use of the temperature gradient in the ocean. They system is to operate between 24.0°C (surface water temperature) and 4.95°C (water temperature at a depth of about 1 km). a. What is the maximum efficiency of such a system? Describe the process that would be used to get this maximum efficiency. b. If the useful power output of the plant is 80.0 MW, how much energy is absorbed per hour?

A 39% maximum efficient coal-fired power plant needs to produce 600 MW of power.  A. To achieve maximum efficiency, if the waste water is dumped into a 13 degree Celsius lake, what temperature must the steam be heated to?  B. Since coal contains 27 kJ of energy per gram, how many kg of coal must be burned in a day?

17.

An aircraft engine takes in 8900 JJ of heat and discards 6700 JJ each cycle. Part A. What is the mechanical work output of the engine during one cycle?   Part B. What is the thermal efficiency of the engine? Express your answer as a percentage.

Over the course of a day, 4.0 kg of water evaporates from the leaves of a corn plant.a. How much energy is required to evaporate the water? (Assume that the temperature of the leaves is 30°C.)b. If the plant is active for 12 hours, how much power does this correspond to? You can think of this as the necessary power to drive transport in the plant.

How much work is needed to lift a bag of groceries that weighs 250N to a height of 4m?   A. 1000 Calorie   B. 1000 J   C. 1000 N   D. 1000 kJ