By how much does the density of air increase when it is compressed to half its volume?

Bacteria have a density that is about the same as water. Their average velocity is 10^-3 m/s. A bacterium with a radius of 1 um should have a diffusion coefficient of about 2.2x10^-13 m^2/s. (a) Find the random-walk step size (b) How long does it take for an average walk to reach 1 mm in seconds and days? Note that we are considering the diffusion away from the starting point and are calculating the distance through three dimensions. Show your work

Balloon angioplasty is a technique to restore blood flow through coronary arteries that have been narrowed by the build-up of plaque. The surgeon threads a catheter into the coronary artery, then inflates a balloon that compresses the plaque against the wall of the artery. Suppose a diseased coronary artery has a diameter of 2.0 mm. To what diameter must it be expanded to increase the blood flow by a factor of 5.0 with no change in pressure?

A light balloon is filled with 397 m3 of helium at atmospheric pressure. (a) At 0°C, the balloon can lift a payload of what mass? kg (b) In the table below, observe that the density of hydrogen is nearly half the density of helium. What load can the balloon lift if filled with hydrogen? | kg Densities of Some Common Substances at Standard Temperature (0°C) and Pressure (Atmospheric) Substance p(kg/m³) p(kg/m3) Substance 0.917 X 10 7.86 X 10 Air 1.29 Ice Aluminum 2.70 X 10 Iron Benzene 0.879 X 103 Lead 11.3 X 10 Copper 8.92 X 103 Mercury 13.6 X 103 Ethyl alcohol Fresh water 0.806 X 10% Oak 0.710 X 10 1.00 X 10 Oxygen gas 1.43 Glycerin 1.26 X 103 Pine 0.373 X 103 19.3 X 10 1.79 X 10-1 21.4 X 10 1.03 X 10 10.5 X 103 Gold Platinum Helium gas Seawater Hydrogen gas 8.99 X 10-2 Silver