The typical diameter of an alveolus is 0.3 mm. The surface tension of water is about 70 dyne cm-1. The dyne is the unit of force in the cgs system: 1 g cm s-2. It is converted to N by multiplying by 10-3kg g-1x 10-2m cm-1 = 10-5 kg g-1 m cm -1. What is the pressure within this alveolus assuming no surfactant at mechanical equilibrium? Give the answer in Pascals (N m-2) and in mm Hg.

Consider two less-than-desirable options. in the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. in the second option you are driving 30 mph and crash head-on into a stationary brick wall. in neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. which of these two situations would result in the greatest impact force?