Problem 1P: What is the difference between the macroscopic and microscopic forms of energy? Problem 2P: What is total energy? Identify the different forms of energy that constitute the total energy. Problem 3P: List the forms of energy that contribute to the internal energy of a system. Problem 4P: How are heat, internal energy, and thermal energy related to each other? Problem 5P: What is mechanical energy? How does it differ from thermal energy? What are the forms of mechanical... Problem 6P: Portable electric heaters are commonly used to heat small rooms. Explain the energy transformation... Problem 7P: Natural gas, which is mostly methane CH4, is a fuel and a major energy source. Can we say the same... Problem 8P: Consider the falling of a rock off a cliff into seawater, and eventually settling at the bottom of... Problem 9P: Electric power is to be generated by installing a hydraulic turbinegenerator at a site 120 m below... Problem 10P: The specific kinetic energy of a moving mass is given by ke = V2/2, where V is the velocity of the... Problem 11P: Determine the specific kinetic energy of a mass whose velocity is 30 m/s, in kJ/kg. Problem 12P: Calculate the total potential energy, in Btu, of an object that is 20 ft below a datum level at a... Problem 13P: Determine the specific potential energy, in kJ/kg, of an object 50 m above a datum in a location... Problem 14P: An object whose mass is 100 kg is located 20 m above a datum level in a location where standard... Problem 15P: A water jet that leaves a nozzle at 60 m/s at a flow rate of 120 kg/s is to be used to generate... Problem 16P: Consider a river flowing toward a lake at an average velocity of 3 m/s at a rate of 500 m3/s at a... Problem 17P: At a certain location, wind is blowing steadily at 10 m/s. Determine the mechanical energy of air... Problem 18P: What is the caloric theory? When and why was it abandoned? Problem 19P: In what forms can energy cross the boundaries of a closed system? Problem 20P: What is an adiabatic process? What is an adiabatic system? Problem 21P: When is the energy crossing the boundaries of a closed system heat and when is it work? Problem 22P: Consider an automobile traveling at a constant speed along a road. Determine the direction of the... Problem 23P: A room is heated by an iron that is left plugged in. Is this a heat or work interaction? Take the... Problem 24P: A room is heated as a result of solar radiation coming in through the windows. Is this a heat or... Problem 25P: A gas in a pistoncylinder device is compressed, and as a result its temperature rises. Is this a... Problem 26P: A small electrical motor produces 5 W of mechanical power. What is this power in (a) N, m, and s... Problem 27P: A car is accelerated from rest to 85 km/h in 10 s. Would the energy transferred to the car be... Problem 28P: A construction crane lifts a prestressed concrete beam weighing 3 short tons from the ground to the... Problem 29P: Determine the torque applied to the shaft of a car that transmits 225 hp and rotates at a rate of... Problem 30P: A spring whose spring constant is 200 lbf/in has an initial force of 100 lbf acting on it. Determine... Problem 31P: How much work, in kJ, can a spring whose spring constant is 3 kN/cm produce after it has been... Problem 32P: A ski lift has a one-way length of 1 km and a vertical rise of 200 m. The chairs are spaced 20 m... Problem 33P: The engine of a 1500-kg automobile has a power rating of 75 kW. Determine the time required to... Problem 34P: A damaged 1200-kg car is being towed by a truck. Neglecting the friction, air drag, and rolling... Problem 35P: As a spherical ammonia vapor bubble rises in liquid ammonia, its diameter changes from 1 cm to 3 cm.... Problem 36P: A steel rod of 0.5 cm diameter and 10 m length is stretched 3 cm. Youngs modulus for this steel is... Problem 37P: What are the different mechanisms for transferring energy to or from a control volume? Problem 38P: For a cycle, is the net work necessarily zero? For what kinds of systems will this be the case? Problem 39P: On a hot summer day, a student turns his fan on when he leaves his room in the morning. When he... Problem 40P: Water is being heated in a closed pan on top of a range while being stirred by a paddle wheel.... Problem 41P: An adiabatic closed system is accelerated from 0 m/s to 30 m/s. Determine the specific energy change... Problem 42P: A fan is to accelerate quiescent air to a velocity of 8 m/s at a rate of 9 m3/s. Determine the... Problem 43P: A vertical pistoncylinder device contains water and is being heated on top of a range. During the... Problem 44P: At winter design conditions, a house is projected to lose heat at a rate of 60,000 Btu/h. The... Problem 45P: A water pump increases the water pressure from 15 psia to 70 psia. Determine the power input... Problem 46P: The lighting needs of a storage room are being met by six fluorescent light fixtures, each fixture... Problem 47P: A university campus has 200 classrooms and 400 faculty offices. The classrooms are equipped with 12... Problem 48P: Consider a room that is initially at the outdoor temperature of 20C. The room contains a 40-W... Problem 49P: An escalator in a shopping center is designed to move 50 people, 75 kg each, at a constant speed of... Problem 50P: Consider a 2100-kg car cruising at constant speed of 70 km/h. Now the car starts to pass another car... Problem 51P Problem 52P: What is mechanical efficiency? What does a mechanical efficiency of 100 percent mean for a hydraulic... Problem 53P: How is the combined pumpmotor efficiency of a pump and motor system defined? Can the combined... Problem 54P: Can the combined turbinegenerator efficiency be greater than either the turbine efficiency or the... Problem 55P: Consider a 2.4-kW hooded electric open burner in an area where the unit costs of electricity and... Problem 56P: The steam requirements of a manufacturing facility are being met by a boiler whose rated heat input... Problem 57P: Reconsider Prob. 256E. Using appropriate software, study the effects of the unit cost of energy, the... Problem 58P: A 75-hp (shaft output) motor that has an efficiency of 91.0 percent is worn out and is replaced by a... Problem 59P Problem 60P: An exercise room has six weight-lifting machines that have no motors and seven treadmills each... Problem 61P: A room is cooled by circulating chilled water through a heat exchanger located in the room. The air... Problem 62P: The water in a large lake is to be used to generate electricity by the installation of a hydraulic... Problem 63P: A 7-hp (shaft) pump is used to raise water to an elevation of 15 m. If the mechanical efficiency of... Problem 64P: A geothermal pump is used to pump brine whose density is 1050 kg/m3 at a rate of 0.3 m3/s from a... Problem 65P: At a certain location, wind is blowing steadily at 7 m/s. Determine the mechanical energy of air per... Problem 66P: Reconsider Prob. 265. Using appropriate software, investigate the effect of wind velocity and the... Problem 67P: Water is pumped from a lower reservoir to a higher reservoir by a pump that provides 20 kW of shaft... Problem 68P: An 80-percent-efficient pump with a power input of 20 hp is pumping water from a lake to a nearby... Problem 69P: Water is pumped from a lake to a storage tank 15 m above at a rate of 70 L/s while consuming 15.4 kW... Problem 70P: Large wind turbines with a power capacity of 8 MW and blade span diameters of over 160 m are... Problem 71P: A hydraulic turbine has 85 m of elevation difference available at a flow rate of 0.25 m3/s, and its... Problem 72P: The water behind Hoover Dam in Nevada is 206 m higher than the Colorado River below it. At what rate... Problem 73P: An oil pump is drawing 44 kW of electric power while pumping oil with = 860 kg/m3 at a rate of 0.1... Problem 74P: A wind turbine is rotating at 15 rpm under steady winds flowing through the turbine at a rate of... Problem 75P: How does energy conversion affect the environment? What are the primary chemicals that pollute the... Problem 76P: What is acid rain? Why is it called a rain? How do the acids form in the atmosphere? What are the... Problem 77P: Why is carbon monoxide a dangerous air pollutant? How does it affect human health at low levels and... Problem 78P: What is the greenhouse effect? How does the excess CO2 gas in the atmosphere cause the greenhouse... Problem 79P: What is smog? What does it consist of? How does ground-level ozone form? What are the adverse... Problem 80P: Consider a household that uses 14,000 kWh of electricity per year and 900 gal of fuel oil during a... Problem 81P: When a hydrocarbon fuel is burned, almost all of the carbon in the fuel burns completely to form CO2... Problem 82P Problem 83P: A typical car driven 20,000 km a year emits to the atmosphere about 11 kg per year of NOx (nitrogen... Problem 84P Problem 85P: What are the mechanisms of heat transfer? Problem 86P: Which is a better heat conductor, diamond or silver? Problem 87P: How does forced convection differ from natural convection? Problem 88P: What is a blackbody? How do real bodies differ from a blackbody? Problem 89P: Define emissivity and absorptivity. What is Kirchhoffs law of radiation? Problem 90P: Does any of the energy of the sun reach the earth by conduction or convection? Problem 91P: The inner and outer surfaces of a 5-m 6-m brick wall of thickness 30 cm and thermal conductivity... Problem 92P: The inner and outer surfaces of a 0.5-cm-thick 2-m 2-m window glass in winter are 15C and 6C,... Problem 93P: Reconsider Prob. 292. Using appropriate software, investigate the effect of glass thickness on heat... Problem 94P Problem 95P Problem 96P Problem 97P Problem 98P: For heat transfer purposes, a standing man can be modeled as a 30-cm-diameter, 175-cm-long vertical... Problem 99P Problem 100P Problem 101P: A 1000-W iron is left on the ironing board with its base exposed to the air at 23C. The convection... Problem 102P: A 7-cm-external-diameter, 18-m-long hot-water pipe at 80C is losing heat to the surrounding air at... Problem 103P: A thin metal plate is insulated on the back and exposed to solar radiation on the front surface. The... Problem 104P: Reconsider Prob. 2103. Using appropriate software, investigate the effect of the convection heat... Problem 105P: The outer surface of a spacecraft in space has an emissivity of 0.6 and an absorptivity of 0.2 for... Problem 106P Problem 107P: A hollow spherical iron container whose outer diameter is 40 cm and thickness is 0.4 cm is filled... Problem 108RP: Some engineers have developed a device that provides lighting to rural areas with no access to grid... Problem 109RP: Consider a classroom for 55 students and one instructor, each generating heat at a rate of 100 W.... Problem 110RP: Consider a homeowner who is replacing his 25-year-old natural gas furnace that has an efficiency of... Problem 111RP Problem 112RP: The U.S. Department of Energy estimates that 570,000 barrels of oil would be saved per day if every... Problem 113RP: A typical household pays about 1200 a year on energy bills, and the U.S. Department of Energy... Problem 114RP Problem 115RP Problem 116RP Problem 117RP: Consider a TV set that consumes 120 W of electric power when it is on and is kept on for an average... Problem 118RP: Water is pumped from a 200-ft-deep well into a 100-ft-high storage tank. Determine the power, in kW,... Problem 119RP: Consider a vertical elevator whose cabin has a total mass of 800 kg when fully loaded and 150 kg... Problem 120RP Problem 121RP: In a hydroelectric power plant, 65 m3/s of water flows from an elevation of 90 m to a turbine, where... Problem 122RP: The demand for electric power is usually much higher during the day than it is at night, and utility... Problem 123RP: The pump of a water distribution system is powered by a 15-kW electric motor whose efficiency is 90... Problem 124RP Problem 125FEP: A 2-kW electric resistance heater in a room is turned on and kept on for 50 min. The amount of... Problem 126FEP Problem 127FEP: A 75-hp compressor in a facility that operates at full load for 2500 h a year is powered by an... Problem 128FEP: On a hot summer day, the air in a well-sealed room is circulated by a 0.50-hp fan driven by a 65... Problem 129FEP: A fan is to accelerate quiescent air to a velocity of 9 m/s at a rate of 3 m3/s. If the density of... Problem 130FEP: A 900-kg car cruising at a constant speed of 60 km/h is to accelerate to 100 km/h in 4 s. The... Problem 131FEP Problem 132FEP Problem 133FEP: A 2-kW pump is used to pump kerosene ( = 0.820 kg/L) from a tank on the ground to a tank at a higher... Problem 134FEP Problem 135FEP Problem 136FEP Problem 137FEP Problem 138FEP: Heat is transferred steadily through a 0.2-m-thick, 8 m 4 m wall at a rate of 2.4 kW. The inner and... Problem 139FEP: The roof of an electrically heated house is 7 m long, 10 m wide, and 0.25 m thick. It is made of a... format_list_bulleted