Week 9 Homework Assignment

1. (P.333 Prob.4) The pressure inside a bottle of champagne is 4.5atm higher than the air pressure outside. The neck of the bottle has an inner radius of 1.0cm. What is the frictional force on the cork due to the neck of the bottle?
2. (P.333 Prob.8) A hydraulic lift, is lifting a car that weighs 12KN. The area of the piston supporting the car is A, the area of the other piston is a, and the ratio A/a is 100.0. How far must the small piston be pushed down to raise the car a distance of 1.0cm? [Hint: Consider the work to be done.]
3. (P.333 Prob.14) The maximum pressure most organism can survive is about 1000 times atmospheric pressure. Only small, simple organisms such as tadpoles and bacteria can survive such high pressures. What then is the maximum depth at which these organisms can live under the sea (assuming that the density of seawater is 1025kg/m³)?
4. (P.334 Prob.24) Estimate the average blood pressure in a person's foot, if the foot is 1.37m below the aorta, where the average blood pressure is 104mm Hg. For the purposes of this estimate, assume the blood isn't flowing.
5. (P.334 Prob.32) An aluminum cylinder weighs 1.03N. When this same cylinder is completely submerged in alcohol, the volume of the displaced alcohol is 3.90 x 10^-5m³. The apparent weight of the cylinder when completely submerged is 0.730N. What is the specific gravity of the alcohol?
6. (P.335 Prob.40) An airplane flies on a level path. There is a pressure difference of 500Pa between the lower and upper surfaces of the wings. The area of each wing surface is about 100m². The air moves below the wings at a speed of 80.5m/s. Estimate (a) the weight of the plane and (b) the speed above the wings.
7. (P.335 Prob.44) A viscous liquid is flowing steadily through a pipe of diameter D. Suppose you replace it by two parallel pipes, each of diameter D/2, but the same length as the original pipe. If the pressure difference between the ends of these two pipes is the same asa for the original pipe, what is the total rate of flow in the two pipes compared to the original flow rate?
8. (P.335 Prob.52) An air bubble of 1.0-mm radius is rising in a container with vegetable oil of specific gravity 0.85 and viscosity 0.12Pa·s. The container of oil and the air bubble are at 20°C. What is its terminal velocity?
9. (P.336 Prob.60)Assume a water strider has a roughly circular foot of radius 0.02mm. (a) What is the maximum possible upward force on the foot due to surface tension of the water? (b) What is the maximum mass of this water strider so that it can keep from breaking through the water surface? The strider has six legs.