The elements in Group 2 have similar chemical properties because each atom of these elements has the same

The concrete slab of a basement is 11 m long, 8 m wide, and 0.20 m thick. During the winter, temperatures are nominally 17°C and

mina [271]

Answer:

$\frac{dQ}{dt}= 4312 W$

Explanation:

As we know that base of the slab is given as

$A = 11 \times 8$

$A = 88 m^2$

now we know that rate of heat transfer is given as

$\frac{dQ}{dt} = \frac{kA}{x} (T_2 - T_1)$

here we know that

$k = 1.4 W/m k$

Also we have

$x =0.20$

$\frac{dQ}{dt} = \frac{1.4(88)}{0.20}(17 - 10)$

$\frac{dQ}{dt}= 4312 W$

7 0

3 years ago

How does the rocket engine work?

Semenov [28]

Answer:

The vacuum of space

Heat management problems

The difficulty of re-entry

Orbital mechanics

Micrometeorites and space debris

Cosmic and solar radiation

The logistics of having restroom facilities in a weightless

Explanation:

5 0

4 years ago

Write the word equation, balanced symbol equations and ionic equation got magnesium carbonate

Finger [1]

Explanation:

Mg-2+C+4>Mg2C.

Here you divide the four by the two and transfer the two toMg. In reactions like this oxidation numbers are exchanged.

7 0

3 years ago

A wall has inner and outer surface temperatures of 25◦C and 8◦C, respectively. The interior and exterior air temperatures are 35

Angelina_Jolie [31]

Answer:

a) $\frac{\dot Q}{A} =60\ W.m^{-2}$

b) $\frac{\dot Q}{A} =110\ W.m^{-2}$

c) The wall may not be under steady because the two surfaces of the wall are exposed to the air at different temperatures and they have different convective coefficient.

Explanation:

Given:

temperature of the inner surface of the wall, $T_i=25^{\circ}C$

temperature of the outer surface of the wall, $T_o=8^{\circ}C$

temperature of the air outside, $T_{ao}=-3^{\circ}C$

temperature of the air inside, $T_{ai}=35^{\circ}C$

coefficient of heat convection on outside, $h_o=10\ W.m^{-2}.K^{-1}$

coefficient of heat convection on inside, $h_i=6\ W.m^{-2}.K^{-1}$

a)

The heat flux between the interior air and the wall:

The convective heat transfer rate is given as,

$Q=h_i.A.\Delta T$

$\Rightarrow \frac{\dot Q}{A} =h_i\times (T_{ai}-T_i)$

$\frac{\dot Q}{A} =6\times (35-25)$

$\frac{\dot Q}{A} =60\ W.m^{-2}$

b)

The heat flux between the exterior air and the wall:

$\Rightarrow \frac{\dot Q}{A} =h_o\times (T_{ao}-T_i)$

$\frac{\dot Q}{A}=10\times (8-(-3))$

$\frac{\dot Q}{A} =110\ W.m^{-2}$

c)

The wall may not be under steady because the two surfaces of the wall are exposed to the air at different temperatures and they have different convective coefficient.

4 0

4 years ago

An AC adapter for a telephone-answering unit uses a transformer to reduce the line voltage of 120 V (rms) to a voltage of 9.0 V.

Illusion [34]

Answer:

1. The number of turns on the secondary output is 18

2. The root mean square power delivered to the transformer is 48 Watts.

Explanation:

A transformer is an electronic device that can be used for increasing or decreasing the value of a given voltage. It consists of primary coils and secondary coil of a definte number of turns. When voltage flows in the primary coil, it induces voltage in the secondary coil. The two types are: step-up and step down transformers.

1. For a given transformer,

$\frac{V_{s} }{V_{p} }$ = $\frac{N_{s} }{N_{p} }$

where $V_{s}$ is the value of the induced voltage in the secondary coil, $V_{p}$ is he voltage in the primary coil, and $N_{s}$ is the number of turns of the secondary coil, $N_{p}$ is the number of turns in the primary coil.