1. Consider a fan located in a 3 ft * 3 ft square duct. Velocities at various points at the outlet are measured, and the average flow velocity is determined to be 22 ft/s. Taking the air density to 0.075 lbm/ft^3 estimate the minimum electric power consumption of the fan motor.
2. Large wind turbines with blade span diameters of over 100m are available for electric power generation. Consider awind turbine with a blade span diameters of 100 m installedat a site subjected to steady winds at 8 m/s. Taking the over-all efficiency of the wind turbine to be 32 percent and theair density to be 1.25 kg/m3generated by this wind turbine. Also, assuming steady windsof 8 m/s during a 24-hour period, determine the amount ofelectric energy and the revenue generated per day for a unitprice of $0.09/kWh for electricity.
3. An adiabatic closed system on earth is accelerated vertically from rest to 25m/s and the system is raised by a height of 110m. The system has a mass of 1.2 kg. If 1.8kJ of work is put into the system, determine the change in internal energy in kJ/kg.
4. A power plant extracts potential energy from a river to provide electrical power. The average amount of water flowing through the plant is 101,000lbm/s. The water intake for the power plant is 676 ft above the exit valves. If the power plant produces 100,000 hp, what is the efficiency of the power plant?