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2 years ago

7

Who is the most genius scientist in the world

1 answer:

aliya0001 [1]2 years ago

6 0

Answer:

Marie Curie

Explanation:

I hope to see you helped :D?

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A football is kicked from ground level with an initial velocity of 23.6 m/s at angle of 57.5° above the horizontal. How long, in

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3 years ago

A 2000 kg car is moving at 15 m/sec when it collides with a 1200 kg car sitting still. Briefly compare the impulse imparted on t

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The 1200 kg car.

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The 1200 kg car had bo momentum at the initial stage of the journey because it wasn't on motion. But after collision with the 2000 kg car it gained alot of momentum.

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3 years ago

The number ocean waves that pass a buoy in one second is _ of the wave

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The number of ocean waves that pass a buoy in one second is the frequency of the <span>wave. The crest of a transverse wave is its highest point. </span>

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3 years ago

Read 2 more answers

The interior space of large box is kept at 30 C. The walls of the box are 3 m high and have a ‘sandwich’ construction consisting

White raven [17]

Answer:

$\frac{\dot Q}{A} =20.129\ W.m^{-2}$

$T_1=27.58\ ^{\circ}C$ & $T_2=2.41875\ ^{\circ}C$

Explanation:

Given:

interior temperature of box, $T_i=30^{\circ}C$

height of the walls of box, $h=3\ m$

thickness of each layer of bi-layered plywood, $x_p=1.25\ cm=0.0125\ m$

thermal conductivity of plywood, $k_p=0.104\ W.m^{-1}.K^{-1}$

thickness of sandwiched Styrofoam, $x_s=5\ cm=0.05\ m$

thermal conductivity of Styrofoam, $k_s=0.04\ W.m^{-1}.K^{-1}$

exterior temperature, $T_o=0^{\circ}C$

<u>From the Fourier's law of conduction:</u>

$\dot Q=\frac{dT}{(\frac{x}{kA}) }$

$\dot Q=\frac{dT}{R_{th} }$ ....................................(1)

<u>Now calculating the equivalent thermal resistance for conductivity using electrical analogy:</u>

$R_{th}=R_p+R_s+R_p$

$R_{th}=\frac{x_p}{k_p.A}+\frac{x_s}{k_s.A}+\frac{x_p}{k_p.A}$

$R_{th}=\frac{1}{A} (\frac{x_p}{k_p}+\frac{x_s}{k_s}+\frac{x_p}{k_p})$

$R_{th}=\frac{1}{A} (\frac{0.0125}{0.104}+\frac{0.05}{0.04}+\frac{0.0125}{0.104})$

$R_{th}=\frac{1.4904}{A}$ .....................(2)

Putting the value from (2) into (1):

$\dot Q=\frac{30-0}{\frac{1.4904}{A} }$

$\dot Q=\frac{30\ A}{1.4904}$

$\frac{\dot Q}{A} =20.129\ W.m^{-2}$ is the heat per unit area of the wall.

The heat flux remains constant because the area is constant.

<u>For plywood-Styrofoam interface from inside:</u>

$\frac{\dot Q}{A} =k_p.\frac{T_i-T_1}{x_p}$

$20.129=0.104\times \frac{30-T_1}{0.0125}$

$T_1=27.58\ ^{\circ}C$

&<u>For Styrofoam-plywood interface from inside:</u>

$\frac{\dot Q}{A} =k_s.\frac{T_1-T_2}{x_s}$

$20.129=0.04\times \frac{27.58-T_2}{0.05}$

$T_2=2.41875\ ^{\circ}C$

4 0

3 years ago

Two resistors A and B are arranged in series in one branch of a parallel arrangement. The other branch contains a single resisto

Ganezh [65]

Answer:

Explanation:

A and B are in series , Total resistance = Ra + Rb

This resistance is in parallel with single resistor C

Equivalent resistance Re = Rc x ( Ra + Rb ) / [Rc + ( Ra + Rb )]

Now this combination is in series in single resistance D .

Total resistance = Rd + Re

= Rd + { Rc x ( Ra + Rb ) / [Rc + ( Ra + Rb )] }

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2 years ago