A frequency quoted rule of thumb aircraft design is that wings should produce about 1000 N of lift per square meter of wing. (The fact that a wing has a top and bottom surface does not double its area.) (a) At takeoff, an aircraft travels at 60.0 m/s, so that the air speed relative to the bottom of the wing is 60.0 m/s. Given be sea level density of air as 1.29kg/m3, how fast must it move over be upper surface to create the ideal lift? (b) How fast must air move over the upper surface at a cruising speed of 245 m/s and at an altitude where air density is one-fourth that at sea level? (Note that his not all of be aircraft's lift—some comes from be body of the plane, some from engine thrust, and so on. Furthermore, Bernoulli's principle gives approximate answer because flow over wing creates turbulence.)

How do gases differ from liquids?

A 75.0-kg floats in freshwater 3.00% of his volume above water when his are empty, and 5.00% of his volume above water when his lungs are full. Calculate the volume of air inhales—called his lung capacity—in liters. (b) Does lung volume seem reasonable?

The average human has a density of 945 kg/m3 after in haling and 1 020 kg/m3 after exhaling. (a) Without making any swimming movements, what percentage of the human body would be above the surface in the Dead Sea (a body of water with a density of about 1 230 kg/m3) in each of these cases? (b) Given that bone and muscle are denser than fat, what physical characteristics differentiate sinkers (those who tend to sink in water) from floaters (those who readily float)?

Bird bones have air pockets to reduce their weight—this also gives them an average density significantly less than that of the bones of other animals. Suppose an ornithologist weighs a bird bone air and in water and finds its mass is 45.0 g ad its apparent mass when submerged is 3.60 g (assume the bone is watertight.)(a) What mass of is displaced? (b) What is the volume of the bone? (c) What is its average density?

Scurrilous con artists have been known to represent gold-plated tungsten ingots as pure gold and sell them at prices much below gold value but high above the cost of tungsten. With what accuracy must you be able to measure the mass of such an ingot in and out of water to tell that it is almost pure tungsten rather than pure gold?

Using the equation of the previous problem, find the viscosity of motor oil in which a steel ball of radius 0.8 mm falls a terminal speed of 4.32 cm/s. The densities of the ball and the oil are 7.86 and 0.88 g/mL, respectively.

Verigy that the SI of hpg is N/m2.

Check Your Understanding Mercury is a hazardous substance. Why do you suppose mercury is typically used in barometers instead of a safer fluid such as water?