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A 40.0-g projectile is launched by the expansion of hot gas in an arrangement shown in Figure P12.4a. The cross sectional area of the launch tube is 1.0 cm2, and the length that the projectile travels down the tube after starting from rest is 52 cm. As the gas expands, the pressure varies as shown in Figure P12.4b. The values for the initial pressure and volume are P1 = 11 × 105 Pa and Vi = 8.0 cm3 while the final values are Pf = 1.0 × 105 Pa and Vf = 8.0 cm3. Friction between the projectile and the launch tube is negligible, (a) If the projectile is launched into a vacuum, what is the speed of the projectile as it leaves the launch tube? (b) If instead the projectile is launched into air at a pressure of 1.0 × 105 Pa. what fraction of the work done by the expanding gas in the tube is spent by the projectile pushing air out of the way as it proceeds down tile tube?
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Chapter 12 Solutions
College Physics
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- How many cubic meters of helium are required to lift a light balloon with a 400-kg payload to a height of 8 000 m? Take Hc = 0.179 kg/m3. Assume the balloon maintains a constant volume and the density of air decreases with the altitude z according to the expression pair = 0e-z/8 000, where z is in meters and 0 = 1.20 kg/m3 is the density of air at sea level.arrow_forwardA gas is in a container of volume V0 at pressure P0. It is being pumped out of the container by a piston pump. Each stroke of the piston removes a volume Vs through valve A and then pushes the air out through valve B as shown in Figure P19.74. Derive an expression that relates the pressure Pn of the remaining gas to the number of strokes n that have been applied to the container. FIGURE P19.74arrow_forwardAn ideal gas is trapped inside a tube of uniform cross-sectional area sealed at one end as shown in Figure P19.49. A column of mercury separates the gas from the outside. The tube can be turned in a vertical plane. In Figure P19.49A, the column of air in the tube has length L1, whereas in Figure P19.49B, the column of air has length L2. Find an expression (in terms of the parameters given) for the length L3 of the column of air in Figure P19.49C, when the tube is inclined at an angle with respect to the vertical. FIGURE P19.49arrow_forward
- The density of air in the Earths atmosphere decreases according to the function =0eh/h0, where 0=1.20kg/m3 is the density of air at sea level and h0 is the scale height of the atmosphere, with an average value of 7640 m. What is the maximum payload that a balloon filled with 2.50 103 m3 of helium (He=0.179kg/m3) can lift to an altitude of 10.0 km?arrow_forwardWhy is the Earths atmosphere denser near sea level than it is at a high altitude? Be sure to explain why the atmospheres density is not uniform and why the air isnt all in contact with the Earths surface.arrow_forward(a) An ideal gas occupies a volume of 1.0 cm3 at 20.C and atmospheric pressure. Determine the number of molecules of gas in the container, (b) If the pressure of the 1.0-cm3 volume is reduced to 1.0 1011 Pa (an extremely good vacuum) while the temperature remains constant, how many moles of gas remain in the container?arrow_forward
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