When a woman is very close to delivering a baby, she may hyperventilate. Breathing into a paper bag regulates herbreathing. How does this action return her breathing to normal ?

Give a reason why it is important to keep blood flow constant and moving in one direction through the body.

Consider the flow of air through a wind turbine whose blades sweep an area of diameter D (in m). The average air velocity through the swept area is V (in m/s). On the bases of the units of the quantities involved, show that the mass flow rate of air (in kg/s) through the swept area is proportional to air density, the wind velocity, and the square of the diameter of the swept area.

Why might Donny be experiencing difficulty breathing?

How much voltage is required to make 2 amperes flow through a resistance of 8 ohms?

Breathing is cyclic and a full respiratory cycle from the beginning of inhalation to the end of exhalation takes about 5 s. The maximum rate of air flow into the lungs is about 0.5 L/s. This explains, in part, why the function $f(t)=\frac{1}{2} \sin \frac{2 \pi t}{5}$ has often been used to model the rate of air flow into the lungs. If inhalation occurs during the interval $0 \leqslant t \leqslant 2.5,$ what is the average rate of air flow during inhalation?

$\mathrm{A}(\mathrm{n})$ valve is used primarily to block fluid flow through a hydraulic system line.

Sequence the events that occur during mammalian breathing.

Water flows through a $25-\mathrm{mm}$ diameter tube that suddenly enlarges to a diameter of $50 \mathrm{~mm}$. The flow rate through the enlargement is $1.25 \mathrm{~Liter} / \mathrm{s}$. Estimate the pressure rise across the enlargement. Compare with the value for friction less flow.

Explain how the breathing rhythm may be changed.

A man consumes 3000 kcal of food in one day, converting most of it to thermal energy to maintain body temperature. If he loses half this energy by evaporating water (through breathing and sweating), how many kilograms of water evaporate?

The flow rate through a blood vessel is found to be $1.5 \times 10^{-7} \mathrm{~m}^3 / \mathrm{s}$. Express this flow rate in units of cubic centimeters per second.

In approximately 5 min, all 5 L of blood in the body pass through the kidneys. Calculate the average rate of flow through the kidneys in liters per minute.

Define surface tension and explain how it aids breathing.