You and your younger brother are designing an air rifle that will shoot a lead pellet with mass m = 1.10 g and cross-sectional area A = 0.030 0 cm3. The rifle works by allowing high-pressure air to expand, propelling the pellet down the rifle barrel. Because this process happens very quickly, no appreciable thermal
Your design also includes a chamber of volume V = 12.0 cm3 in which the high-pressure air is stored until it is released. Your brother reminds you that you need to purchase a pump to pressurize the chamber. To determine what kind of pump to buy, you need to find what the pressure of the air must be in the chamber to achieve your desired muzzle speed. Ignore the effects of the air in front of the bullet and friction with the inside walls of the barrel.
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Chapter 20 Solutions
Physics for Scientists and Engineers
- An ideal gas initially at 300 K undergoes an isobaric expansion at 2.50 kPa. If the volume increases from 1.00 m3 to 3.00 m3 and 12.5 kJ is transferred to the gas by heat, what are (a) the change in its internal energy and (b) its final temperature?arrow_forwardAn aluminum rod 0.500 m in length and with a cross-sectional area of 2.50 cm2 is inserted into a thermally insulated vessel containing liquid helium at 4.20 K. The rod is initially at 300 K. (a) If one-half of the rod is inserted into the helium, how many liters of helium boil off by the time the inserted half cools to 4.20 K? Assume the upper half does not yet cool. (b) If the circular surface of the upper end of the rod is maintained at 300 K, what is the approximate boil-off rate of liquid helium in liters per second after the lower half has reached 4.20 K? (Aluminum has thermal conductivity of 3 100 W/m K at 4.20 K; ignore its temperature variation. The density of liquid helium is 125 kg/m3.)arrow_forwardWhen a gas undergoes an adiabatic expansion, which of the following statements is true? (a) The temperature of the gas does not change. (b) No work is done by the gas. (c) No energy is transferred to the gas by heat. (d) The internal energy of the gas does not change. (e) The pressure increases.arrow_forward
- For a temperature increase of 10 at constant volume, what is the heat absorbed by (a) 3.0 mol of a dilute monatomic gas; (b) 0.50 mol of a dilute diatomic gas; and (c) 15 mol of a dilute polyatomic gas?arrow_forwardDuring the power stroke in a four-stroke automobile engine, the piston is forced down as the mixture of combustion products and air undergoes an adiabatic expansion. Assume (1) the engine is running at 2 500 cycles/min; (2) the gauge pressure immediately before the expansion is 20.0 atm; (3) the volumes of the mixture immediately before and after the expansion are 50.0 cm3 and 400 cm3, respectively (Fig. P21.31); (4) the time interval for the expansion is one-fourth that of the total cycle; and (5) the mixture behaves like an ideal gas with specific heat ratio 1.40. Find the average power generated during the power stroke.arrow_forwardHow much energy must be transferred as heat for a reversible isothermal expansion of an ideal gas at 132 degrees Celcius if the enthropy of the gas increases by 46.0 J/Karrow_forward
- In an engine, 0.25 mol of an ideal monatomic gas in the cylinder expands rapidly and adiabatically against the piston. In the process, the temperature of the gas drops from 1150 K to 400 K. How much work does the gas do?arrow_forwardWhat happens to the internal energy of a gas during an adiabatic expansion?arrow_forwardThe temperature of 2.00 mol of an ideal monatomic gas is raised 15.0 K in an adiabatic process.What are (a) the work W done by the gas, (b) the energy transferred as heat Q, (c) the change Eint in internal energy of the gas, and (d) the change K in the average kinetic energy per atomarrow_forward
- A 1.0 m * 1.5 m double-pane window consists of two 4-mm-thick layers of glass (k = 0.78 W/m·K) that are separated by a 5-mm air gap (kair = 0.025 W/m·K). The heat flow through the air gap is assumed to be by conduction. The inside and outside air temperatures are 20°C and 220°C, respectively, and the inside and outside heat transfer coefficients are 40 and 20 W/m2·K. Determine (a) the daily rate of heat loss through the window in steady operation and (b) the temperature difference across the largest thermal resistance.arrow_forwardA quantity of a monatomic ideal gas undergoes a process in which both its pressure and volume are doubled as shown in Figure P12.18. What is the energy absorbed by heat into the gas during this process? Hint: The internal energy of a monatomic ideal gas at pressure P and occupying volume V is given by U = 3/2PVarrow_forwardA certain molecule has f degrees of freedom. Show that an ideal gas consisting of such molecules has the following properties: (a) its total internal energy is fnRT/2, (b) its molar specific heat at constant volume is fR/2, (c) its molar specific heat at constant pressure is (f + 2)R/2, and (d) its specific heat ratio is γ = CP/CV = (f + 2)/f.arrow_forward
- Physics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning