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viktelen [127]
2 years ago
8

The amount of heat per second conducted from the blood capillaries beneath the skin to the surface is 250 j/s. the energy is tra

nsferred a distance of 2.1 × 10-3 m through a body whose surface area is 1.9 m2. assuming that the thermal conductivity is that of body fat, determine the temperature difference between the capillaries and the surface of the skin.
Physics
1 answer:
marin [14]2 years ago
5 0
Heat flux (i) = k.a.temp variation/d
i = 250 J/s or 250w ; d = 2.1 x 10^-3m ; A = 1.9m^2 ; K (Body Fat) = 0.2W/m.Kelvin ; Temp. Var. (Delta T) = ?

-> 250 = 0.2 x 1.9 x deltaT/2.1 x 10^-3
-> 250 x 2.1 x 10^-3 = 0.38 x deltaT
-> 525 x 10^-3 = 38x10^-2 x deltaT
-> deltaT = 525 x 10^-3/ 38 x 10^-2
-> deltaT = 13.81 x 10^(-3 - (-2))
-> deltaT = 13.81 x 10^-1
-> deltaT = 1.381 K
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Un objeto de 200 gramos está amarrado del extremo de una cuerda y gira describiendo un círculo horizontal de 1.20 m de radio a r
vesna_86 [32]

Answer:

La tensión es 85.3 N.

Explanation:

Cuando el objeto gira en dirección horizontal, la sumatoria de fuerzas se puede calcular usando la segunda ley de Newton:  

\Sigma F_{x} =ma_{c}

T = ma_{c}  

Dado que el movimiento es horizontal, el peso (que está en el eje y) no contribuye en la sumatoria de fuerzas en el eje x. Por lo que la única fuerza actuando sobre el objeto en la dirección del movimiento es la tensión.  

En donde:                                          

m: es la masa del objeto = 200 g = 0.200 kg

a_{c}: es la aceleración centrípeta

La aceleración centrípeta viene dada por:  

a_{c} = \omega^{2} r

En donde:    

ω: es la velocidad angular del objeto = 3 rev/s

r: es el radio = 1.20 m

Entonces, la tensión es:

T = m\omega^{2} r = 0.200 kg(3\frac{rev}{s}*\frac{2\pi rad}{1 rev})^{2}*1.20 m = 85.3 N

   

Por lo tanto, la tensión es 85.3 N.  

Espero que te sea de utilidad!                                                                          

5 0
2 years ago
A car is traveling at 120 km/h (75 mph). When applied the braking system can stop the car with a deceleration rate of 9.0 m/s2.
Bumek [7]

Answer:

the number of additional car lengths approximately it takes the sleepy driver to stop compared to the alert driver is 15

Explanation:

Given that;

speed of car V  = 120 km/h = 33.3333 m/s

Reaction time of an alert driver = 0.8 sec

Reaction time of an alert driver = 3 sec

extra time taken by sleepy driver over an alert driver = 3 - 0.8 = 2.2 sec

now, extra distance that car will travel in case of sleepy driver  will be'

S_d = V × 2.2 sec

S_d = 33.3333 m/s × 2.2 sec

S_d = 73.3333 m

hence, number of car of additional car length  n will be;

n = S_n / car length

n = 73.3333 m / 5m

n = 14.666 ≈ 15

Therefore, the number of additional car lengths approximately it takes the sleepy driver to stop compared to the alert driver is 15

8 0
3 years ago
At which point would most of the pendulum's potential energy have been transformed into kinetic energy?
Bess [88]

Answer:

C

Explanation:

i could be wrong but it seems the most logical

6 0
3 years ago
A 2300 kg sailboat is moving west at 5.5 m/s when an eastward wind
pogonyaev

The boat is initially at equilibrium since it seems to start off at a constant speed of 5.5 m/s. If the wind applies a force of 950 N, then it is applying an acceleration <em>a</em> of

950 N = (2300 kg) <em>a</em>

<em>a</em> = (950 N) / (2300 kg)

<em>a</em> ≈ 0.413 m/s²

Take east to be positive and west to be negative, so that the boat has an initial velocity of -5.5 m/s. Then after 11.5 s, the boat will attain a velocity of

<em>v</em> = -5.5 m/s + <em>a</em> (11.5 s)

<em>v</em> = -0.75 m/s

which means the wind slows the boat down to a velocity of 0.75 m/s westward.

5 0
3 years ago
What is the particles instantaneous speed at t=16 sec
Ira Lisetskai [31]

It's  3.6 meters per second less than my speed was
at 4:19 PM last Tuesday.

Does that tell you anything ?
Why not ?

 
8 0
3 years ago
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