1.48 assume that the air volume in a small automobile tire is constant and equal to the volume between two concentric cylinders 13 cm high with diameters of 33 cm and 52 cm. the air in the tire is initially at 25 °c and 202 kpa. immediately after air is pumped into the tire, the temperature is 30 °c and the pressure is 303 kpa. what mass of air was added to the tire? what would be the air pressure after the air has cooled to a temperature of 0 °c?

a) 0.018 kg

b) 262 kPa

Explanation:

The volume of the concentric cylinders would be:

V = π/4 * h * (D^2 - d^2)

V = π/4 * 13 * (52^2 - 33^2) = 16500 cm^3 = 0.0165 m^3

The state equation of gases:

p * V = m * R * T

Rearranging:

m = (p * V) / (R * T)

R is 287 J/(kg * K) for air

25 C = 298 K

m0 = 202000 * 0.0165 / (287 * 298) = 0.039 kg

After pumping more air the volume remains about the same, but temperature and pressure change.

30 C = 303 K

m1 = 303000 * 0.0165 / (287 * 303) = 0.057 kg

The mass that was added is

m1 - m0 = 0.057 - 0.039 = 0.018 kg

If that air is cooled to 0 C

0 C  is 273 K

p = m * R * T / V

p = 0.057 * 278 * 273 / 0.0165 = 262000 Pa = 262 kPa

bacteria that live on the ocean floor are sustained by phytoplankton. phytoplankton, microscopic marine photosynthetic organisms, have a vastly significant role to play not only in the marine food web of which they’re part of, but also on a more global scale. despite their infinitely small size in comparison to other marine organisms, these tiny creatures occupy an immensely important ecological niche: they are the foundation of the marine food web, and as primary producers, play key roles in supporting all other organisms in the marine environment, as well as in the regulation of the earth’s climate through the sequestration of carbon, oxygen production, and other related processes. phytoplankton account for roughly half of all global primary productivity; therefore, their significance extends far beyond the marine environment alone. there is an intriguing sense of irony in the realization that these tiny living beings that often live out their existence unnoticed and undetected by the rest of the world, have such a far-reaching impact on the lives of virtually all other living organisms on the planet, particularly on those in the marine environment. the world that we have become accustomed to has been and is continuously shaped by the workings of these miniscule yet vital “plants of the sea”.

hope this !