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faltersainse [42]
2 years ago
13

The blood plays an important role in removing heat from th ebody by bringing the heat directly to the surface where it can radia

te away. nevertheless, this heat must still travel through the skin before it can radiate away. we shall assume that the blood is brought to the bottom layer of skin at a temperature of 37.0 degrees C and that its outer surface of the skin is at 30.0 degrees C. Skin varies in thickness from 0.500mm to a few millimeters on the palms and the soles so we shall assume an average thickness off 0.740mm. a 165lb, 6 ft person has a surface area of about 2.00 m^2 and loses heat at a net rate of 75.0 w while resting. On the basis of our assumptions, what is the thermal conductivity of this persons skin?
Physics
1 answer:
BabaBlast [244]2 years ago
7 0

Answer: Thermal comductivity (K) is 3.964x 10 ^-3 W/m.k

Explanation:

Thermal comductivity K = QL/A∆T

Q= Amount of heat transferred through the material in watts = 75W

L= Distance between two isothermal planes = 0.740mm

A= Area of the surface in square metres = 2m^2

∆T= Temperature change = (37-30) °C.

Solving this : K =( 75 x 0.740 x 10^-3)/ 2 x (37-30)

K = 3.964x 10 ^-3 W/m.k

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A particle traveling in a circular path of radius 300 m has an instantaneous velocity of 30 m/s and its velocity is increasing a
grigory [225]
<h2>Answer:</h2>

(c) 5m/s²

<h2>Explanation:</h2>

Total acceleration (a) of a particle in a circular motion is the vector sum of the radial or centripetal acceleration (a_{C}) of the particle and the tangential acceleration (a_{T}) of the particle and its magnitude can be calculated as follows;

a = \sqrt{(a_{C})^2 + (a_{T})^2}           ---------------------(i)

<em>But;</em>

a_{C} = \frac{v^{2} }{r}      ------------------------------(ii)

Where;

v = instantaneous velocity

r =  radius of the circular path of motion

<em>From the question;</em>

v = 30m/s

r = 300m

(i) First let's calculate the centripetal acceleration by substituting the values above into equation (ii) as follows;

a_{C} = \frac{30^{2} }{300}

a_{C} = \frac{900}{300}

a_{C} = 3m/s²

(ii) From the question, the velocity of the particle is increasing at a constant rate of 4m/s²  and that is the tangential acceleration a_{T}, of the particle. i.e;

a_{T} = 4m/s²

(iii) Now substitute the values of a_{C} and a_{T} into equation (i) as follows;

a = \sqrt{(3)^2 + (4)^2}

a = \sqrt{(9) + (16)}

a = \sqrt{25}

a = 5m/s²

Therefore, the magnitude of its total acceleration a, is 5m/s²

5 0
2 years ago
Sebuah benda dijatuhkan bebas dari ketinggian 200 m jika grafitasi setempat 10 m/s maka hitunglah kecepatan dan ketinggian benda
Pie
Please post in English so i or someone else can help you.
7 0
2 years ago
If Pete ( mass=90.0kg) weights himself and finds that he weighs 30.0 pounds, how far away from the surface of the earth is he
shutvik [7]

Answer: 9938.8 km

Explanation:

1 pound-force = 4.48 N

30.0 pounds-force = 134.4 N

The force of gravitation between Earth and object on the surface of is given by:

F = \frac{GMm}{R^2} = mg

Where M is the mass of the Earth, m is the mass of the object, R (6371 km) is the radius of the Earth.

At height, h above the surface of the Earth, the weight of the object:

(mg)'= \frac{GMm}{(R+h)^2}

we need to find "h"

taking the ratio of two:

\frac{mg}{(mg)'}=\frac{(R+h)^2}{R^2}\\ \Rightarrow \frac{90kg \times 9.8 m/s^2}{134.4 N}=\frac{(R+h)^2}{R^2}\\ \Rightarrow 6.56 R^2= (R+h)^2 \Rightarrow h= (2.56-1)R\\ \Rightarrow h = 1.56 R = 1.56 \times 6371 km = 9938. 8 km

Hence, Pete would weigh 30 pounds at 9938.8 km above the surface of the Earth.

5 0
2 years ago
Charge is distributed uniformly on the surface of a large flat plate. the electric field 2 cm from the plate is 30 n/c. the elec
AysviL [449]
The electric field produced by a large flat plate with uniform charge density on its surface can be found by using Gauss law, and it is equal to
E= \frac{\sigma}{2\epsilon_0}
where
\sigma is the charge density
\epsilon_0 is the vacuum permittivity

We see that the intensity of the electric field does not depend on the distance from the plate. Therefore, the strenght of the electric field at 4 cm from the plate is equal to the strength of the electric field at 2 cm from the plate:
E=30 N/C
7 0
2 years ago
A box sits on a table. A short arrow labeled F subscript N points up. A short arrow labeled F subscript g points down. A long ar
Aloiza [94]

Answer:

unbalanced and right

Explanation:

7 0
2 years ago
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