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2 years ago

How is the surface area to volume ratio maximized in lungs?

1 answer:

8 0

There are branches on the lungs making it resemble a tree. These branches have sacs called alveoli that look like grape bunches. The combination of branching and alveoli maximize lung surface area.<span>
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For heat transfer purposes, an egg can be considered to be a 5.5-cm-diameter sphere having the properties of water. An egg that

Harrizon [31]

Answer:

The time taken is $t = 40007 sec$

Explanation:

From the question we are told that

The diameter of the egg is $d_e = 5.5cm = \frac{5.5}{100} = 5.5*10^{-2}m$

The initial temperature of egg the $T_e = 4.3^{o}C$

The temperature of the boiling water $T_b = 100^oC$

The heat transfer coefficient is $H = 800 W/m^2 \cdot K$

The final temperature is $T_e_f = 74^oC$

The thermal conductivity of water is $k = 0.607 W/m^oC$

The diffusivity of the egg $\alpha = 0.146 * 10^{-6} m^2 /s$

Using one term approximation

We have the

$\frac{T_e_f - T_b}{T_e - T_b} = Ae^{-\lambda ^2 \tau}$

The radius is $r = \frac{5.5*10^ {-2}}{2} =2.75*10^{-2}m$ Note that this radius is approximation to that of a real egg

Now we need to obtain the Biot number which help indicate the value of $A \ and \ \lambda$ to use in the above equation

The Biot number is mathematically represented as

$Bi = \frac{H r}{k}$

Substituting values

$Bi = \frac{800 * 2.75 *10^{-2}}{0.607}$

$= 36.24$

So for this value which greater than 0.1 the coefficient $\lambda_1 \ and \ A_1$ is

$\lambda = 3.06632$

$A = 1.9942$

Substituting this into equation 1 we have

$\frac{74- 100}{4.3 - 100} = 1.9942 e^{-(3.0632^2) \tau}$

$0.2717= 1.9942 e^{-(3.0632^2) \tau}$

$0.2717= 1.9942 e^{-9.383 \tau}$

$0.13624 = e^{-9.383 \tau}$

Taking natural log of both sides

$-1.993 = -9.383\ \tau$

$\tau = 0.2124$

The time required for the egg to be cooked is mathematically represented as

$t = \frac{\tau r^2}{\alpha }$

substituting value is

$= \frac{0.2124 * 2.75 *10^{-2}}{0.146 *10^{-6}}$

$t = 40007 sec$

8 0

2 years ago

Rocket-powered sleds are been used to test the responses of humans to acceleration. Starting from rest, one sled can reach a spe

Greeley [361]

Answer:cho v₀ =0s

α=Δv/Δt

Explanation:

$\frac{0-495}{2,16-1,78}$

=-1302,631579

chuyển động chậm dầnđều

3 0

2 years ago

The West the cost

poizon [28]

Answer:

Sck my p3nis

Explanation:

if you do so, then your mom will have coronavirus.

4 0

2 years ago

A 500-kg roller coaster car travels with some initial velocity along a track that is 5 m above the ground. The car goes down a s

LUCKY_DIMON [66]

Answer:

12m/s

Explanation:

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2 years ago

What is the name of the space telescope in low earth orbit that was launched in 1990?

Mrrafil [7]

The Hubble Space Telescope is a joint ESA/NASA project and was launched in 1990 by the Space Shuttle mission STS-31 into a low-Earth orbit 569 km above the ground. During its lifetime Hubble has become one of the most important science projects ever. Hope this helps! ~ Autumn :)

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2 years ago