BackWhen a person drives or hikes to a higher altitude, and even more during descent, volume changes of trapped air in the middle ear can cause ear discomfort until the middle-ear pressure and exterior pressure are equalized.
(a) If a rapid descent at a rate of 7.0 m/s or faster commonly causes ear discomfort, what is the maximum rate of increase in atmospheric pressure (that is, dP/dt) tolerable to most people?
When you ascend or descend a great deal when driving in a car, your ears “pop,” which means that the pressure behind the eardrum is being equalized to that outside. If this did not happen, what would be the approximate force on an eardrum of area 0.20cm² if a change in altitude of 1120 m takes place?
(I) A marble column of cross-sectional area 1.4m² supports a mass of 22,000 kg.
(c) By how much is the column shortened if it is 8.6 m high?
Parachutists whose chutes have failed to open have been known to survive if they land in deep snow. Assume that a 75-kg parachutist hits the snow with an area of impact of .030m² at a velocity of 55 m/s, and that the ultimate strength of body tissue is 5 x 10⁵ N/m². Assume that the person is brought to rest in 1.0 m of snow. Show that the person may escape serious injury.
Suppose a 65-kg person jumps from a height of 3.0 m down to the ground.
(e) Estimate the stress and determine if the tibia will break in a stiff-legged landing ( d = 1.0 cm).
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