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Andrew [12]
2 years ago
12

You have a tungsten sphere (emissivity ε = 0.35) of radius 25 cm at a temperature of 25°C. If the sphere is enclosed in a room w

hose walls are kept at -5°C, what is the net flow rate of energy out of the sphere?
Physics
1 answer:
egoroff_w [7]2 years ago
8 0

Answer:

Explanation:

Stefan's formula for emission of radiation is

E = e σ A  ( T⁴ - T₀⁴ )

E is energy radiated , e is emissivity , σ is stefan's constant , T is temperature of object and T₀ is temperature of surrounding. A is area of surface .

E = .35 x 5.67 x 10⁻⁸ ( 298⁴ - 268⁴ ) x 4π x .25²

= 1.9845 x 10⁻⁸ ( 78.86 - 51.58 ) x 10⁸ x .0625

= 3.38  J /s

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sdas [7]

Answer:

Explanation:

90 rpm = 90 / 60 rps

= 1.5 rps

= 1.5 x 2π rad /s

angular velocity of flywheel

ω = 3π rad /s

Let I be the moment of inertia of flywheel

kinetic energy = (1/2) I ω²

(1/2) I ω² = 10⁷ J

I = 2 x  10⁷ / ω²

=2 x  10⁷ / (3π)²

= 2.2538 x 10⁵ kg m²

Let radius of wheel be R

I = 1/2 M R² , M is mass of flywheel

= 1/2 πR² x t x d x R² , t is thickness , d is density of wheel .

1/2 πR⁴ x t x d = 2.2538 x 10⁵

R⁴ = 2 x 2.2538 x 10⁵ / πt d

= 4.5076 x 10⁵ / 3.14 x .1 x 7800

= 184

R= 3.683 m .

diameter = 7.366 m .

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3 0
2 years ago
A wire along the z axis carries a current of 4.9 A in the z direction Find the magnitude and direction of the force exerted on a
AURORKA [14]

Answer:

<h2>0.069 N, in the X direction</h2>

Explanation:

According to Flemming's left hand rule, it sates that if the first three fingers of the left hand are held mutually at right angles to one another, the fore finger will point in the direction of magnetic field, the middle finger will point in direction of current, while the thumb will point to the direction of force.

Mathematically the law is stated as

F= BIL

given data

Magnetic field B=  0.43T

Current I= 4.9 A

length of conductor L= 3.3cm to meter , 3.3/100=  0.033 m

Applying the formula the force is calculated as

F= 0.43*4.9* 0.033= 0.069 N

According to Flemming's rule the direction of all parameters are mutually perpendicular to one another, then the Force is in the X direction

5 0
3 years ago
Why is it not posible to see the other waves on the electromagnetic spectrum???
Montano1993 [528]
It is not possible to see the other waves on the electromagnetic spectrum because only other species can see the other parts of the spectrum because they have different components in their eyes than we do, therefore, only allowing us to see a
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3 years ago
I’m so confused someone help
Lena [83]
Thermal- transfer of heat thru space
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4 0
2 years ago
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A body weighs 100newtons and 80newtons when submerged in water.calculate the upthrust action on the body
katovenus [111]

Answer:

20 N

Explanation:

In air, the normal force is equal to the weight.

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Submerged in water, the normal force is equal to the weight minus the buoyant force:

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Plugging in values:

80 N = 100 N − B

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3 0
3 years ago
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