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zavuch27 [327]
3 years ago
15

What is the rate of heat transfer by radiation, with an unclothed person standing in a dark room whose ambient temperature is 22

.0ºC . The person has a normal skin temperature of 33.0ºC and a surface area of 1.50 m2. The emissivity of skin is 0.97 in the infrared, where the radiation takes place.
Physics
1 answer:
SIZIF [17.4K]3 years ago
3 0

Answer:

5.45\times 10^{-4} W

Explanation:

T_{r} = Temperature of the room = 22.0 °C = 22 + 273 = 295 K

T_{s} = Temperature of the skin = 33.0 °C = 33 + 273 = 306 K

A = Surface area = 1.50 m²

\epsilon = emissivity = 0.97

\sigma = Stefan's constant = 5.67 x 10⁻⁸ Wm⁻² K⁻⁴

Rate of heat transfer is given as

R = \epsilon \sigma A (T_{s}^{2} - T_{r}^{2})

R = (0.97)(5.67\times 10^{-8}) (1.50) ((306)^{2} - (295)^{2})

R = 5.45\times 10^{-4} W

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Formula for the distance (d) is given by d = rate*time. For example if you are traveling at 60 mph for 3 hours the distance trav
babunello [35]

Explanation:

Distance covered by the particle is given by:

Distance (d) = rate (v) × time (t)                

Speed of Mary, v₁ = 50 mph

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It is assumed that, Mary and Jim leave at the same time. After one hour, Jim is 10 miles ahead.

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t\ge9\ h

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7 0
3 years ago
For a cylindrical capacitor, the capacitance does not depend on which of the following values?
IgorC [24]

Answer:

Capacitance of cylindrical capacitor does not depends on the amount of charge on the conductors

Explanation:

Consider a cylindrical capacitor of length L, inner radius R₁ and outer radius R₂, permitivity ε₀ constant then capacitance of cylindrical capacitor is given by:

C=\frac{2\pi \epsilon_{o}L}{ln\frac{R_{2} }{R_{1}} }

From this equation it is clear that capacitance of cylindrical capacitor is independent of the amount of charge on the conductors where as directly  proportional permitivity constant and length of cylinder where as inversely proportional to natural log of ratio of  R₂ and R₁

5 0
3 years ago
A certain car can accelerate from 0 to 60 mph in 7.9 s. What is the car's average acceleration in mph/s?
Anna007 [38]

Answer:

<em>a = 7.6\ mph/s</em>

Explanation:

<u>Motion With Constant Acceleration </u>

It's a type of motion in which the velocity of an object changes uniformly in time.

The equation that describes the change of velocities is:

v_f=v_o+at

Where:

a   = acceleration

vo = initial speed

vf  = final speed

t    = time

Solving the equation [for a:

\displaystyle a=\frac{v_f-v_o}{t}

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\displaystyle a=\frac{60 \ mph-0}{7.9}

a = 7.6\ mph/s

7 0
3 years ago
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