During typical urination, a man releases about 400 mL of urine in about 30 seconds through the urethra, which we can model as a tube 4 mm in diameter and 20 cm long. Assume that urine has the same density as water, and that viscosity can be ignored for this flow. a. What is the flow speed in the urethra

The flow speed in the urethra is 3.77 m/s

Explanation:

The flow rate or speed of a liquid is a measure of the volume of liquid that flows in a given amount of time.

Fluid flow rate, Q = area of the pipe or channel × velocity of the liquid

Q = A × v ; where Q is  in m³/s or L/s; A is in m²; velocity, v = is in m/s

Also flow rate, Q = volume/time

volume, V, is in m³ and time is in seconds

therefore, V/t = A × v

v = At / V

Volume, V = 400 mL = 0.4 L = 4 × 10⁻⁴ m³

Area, A, of tube = πr², where r is radius in meters

r = 4 mm = 4 × 10⁻³ m

A = 22/7 × (4 × 10⁻³ m)²

therefore, v = {22/7 × (4 × 10⁻³ m)² × 30}/4 × 10⁻⁴ m³

v = 3.77 m/s

Therefore, the flow speed in the urethra is 3.77 m/s

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."    

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.