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2 years ago

IF YOU GET GOOD GRADES ON SCIENCE TESTS PLEASE HELP ME!!!!!

Physics

2 answers:

ExtremeBDS [4]2 years ago

6 0

Answer:

it is 21

Explanation:

FromTheMoon [43]2 years ago

6 0

The answer would be B!

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Consider a 20 cm thick granite wall with a thermal conductivity of 2.79 W/m·K. The temperature of the left surface is held const

kozerog [31]

Answer:

The right wall surface temperature and heat flux through the wall is 35.5°C and 202.3W/m²

Explanation:

Thickness of the wall is L= 20cm = 0.2m

Thermal conductivity of the wall is K = 2.79 W/m·K

Temperature at the left side surface is T₁ = 50°C

Temperature of the air is T = 22°C

Convection heat transfer coefficient is h = 15 W/m2·K

Heat conduction process through wall is equal to the heat convection process so

$Q_{conduction} = Q_{convection}$

Expression for the heat conduction process is

$Q_{conduction} = \frac{K(T_1 - T)}{L}$

Expression for the heat convection process is

$Q_{convection} = h(T_2 - T)$

Substitute the expressions of conduction and convection in equation above

$Q_{conduction} = Q_{convection}$

$\frac{K(T_1 - T_2)}{L} = h(T_2 - T)$

Substitute the values in above equation

$\frac{2.79(50- T_2)}{0.2} = 15(T_2 - 22)\\\\T_2 = 35.5^\circC$

Now heat flux through the wall can be calculated as

$q_{flux} = Q_{conduction} \\\\q_{flux} = \frac{K(T_1 - T_2)}{L}\\\\q_{flux} = \frac{2.79(50 - 35.5)}{0.2}\\\\q_{flux} = 202.3W/m^2$

Thus, the right wall surface temperature and heat flux through the wall is 35.5°C and 202.3W/m²

6 0

2 years ago

Suppose two point charges, Q1 = -6.25 x 10-9 C and Q2 = -6.25 x 10-9 C, are separated by a distance d = 0.617 m.

n200080 [17]

Answer:

The answer to your question is the letter A) F = 9.23 x 10⁻⁷ N

Explanation:

Data

q₁ = -6.25 x 10⁻⁹ C

q₂ = -6.25 x 10⁻⁹ C

d = 0.617 m

k = 9 x 10⁹ Nm²/C²

F = ?

Formula

F = k q₁q₂ /r²

-Substitution

F = (9 x 10⁹)(-6.25 x 10⁻⁹)(-6.25 x 10⁻⁹) / (0.617)²

-Simplification

F = 3.512 x 10⁻⁷ / 0.381

-Result

F = 9.227 x 10⁻⁷ N ≈ 9.23 x 10⁻⁷ N

8 0

2 years ago

Which statement expresses the relationship between the frequency of emitted electrons and the energy they give off?

Nadusha1986 [10]

I think it would be the first choice

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3 years ago

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When an ice cube is placed in a glass of warm water, how are the signs and values q for the ice and the warm water related, assu

Valentin [98]

Answer:

q(ice) = -q(warm water)

Explanation:

Ice removes energy if ice is put in warm water and ice retains the very same amount of energy. Thus the water temperature heat sign is negative, and the ice heat sign is positive.

3 0

2 years ago

A short, thick wire is the best conductor. True or false?

Firdavs [7]

I believe that the answer is true!

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2 years ago

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