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2 years ago

Three natural materials that were used by early man as roof covering

Engineering

2 answers:

olga55 [171]2 years ago

8 0

Explanation:

animal parts, wood, rock, and clay

Law Incorporation [45]2 years ago

8 0

Answer:

roofing sheet

wood

metal

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(a) In a 3-phase, 4-wire system, the currents are in the A, B, and C lines under abnormal conditions of loading were as follows:

Verizon [17]

Answer:

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Explanation:

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2 years ago

A piston-cylinder device contains an ideal gas mixture of 3 kmol of He gas and 7 kmol of Ar gas (both gases are monatomic) at 27

lidiya [134]

Answer:

Q = 62 ( since we are instructed not to include the units in the answer)

Explanation:

Given that:

$n_{HCl} = 3 \ kmol\\n_{Ar} = 7 \ k mol$

$T_1 = 27^0 \ C = ( 27+273)K = 300 K$

$P_1 = 200 \ kPa$

Q = ???

Now the gas expands at constant pressure until its volume doubles

i.e if $V_1 = x\\V_2 = 2V_1$

Using Charles Law; since pressure is constant

$V \alpha T$

$\frac{V_2}{V_1} =\frac{T_2}{T_1}$

$\frac{2V_1}{V_1} =\frac{T_2}{300}$

$T_2 = 300*2\\T_2 = 600$

mass of He =number of moles of He × molecular weight of He

mass of He = 3 kg × 4

mass of He = 12 kg

mass of Ar =number of moles of Ar × molecular weight of Ar

mass of He = 7 kg × 40

mass of He = 280 kg

Now; the amount of Heat Q transferred = $m_{He}Cp_{He} \delta T + m_{Ar}Cp_{Ar} \delta T$

From gas table

$Cp_{He} = 5.9 \ kJ/Kg/K\\Cp_{Ar} = 0.5203 \ kJ/Kg/K$

∴ Q = $12*5.19*10^3(600-300)+280*0.5203*10^3(600-300)$

Q = $62.389 *10^6$

Q = 62 MJ

Q = 62 ( since we are instructed not to include the units in the answer)

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3 years ago

Read 2 more answers

Why is it reasonable to say that no system is 100% efficient?

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Generally, frictional losses are more predominant for the machines being not 100% efficient. This friction leads to the loss of energy in the form of heat, into the surroundings. Some of the supplied energy may be utilised to change the entropy (measure of randomness of the particles) of the system.

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2 years ago

Most of the work that engineers do with fluids occurs in nature. True False

zlopas [31]

True depending the jobs

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2 years ago

What is the function rule for the line? f(x)=−32x−2f(x)=−23x−2f(x)=32x−2f(x)=−32x+2A coordinate grid with x and y axis ranging f

murzikaleks [220]

Answer:

f(x)=23x−2

Explanation:

still trying to figure that out

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3 years ago

Three natural materials that were used by early man as roof covering​

Three natural materials that were used by early man as roof covering