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3 years ago

5

Find the total amount of heat in Q lost through a wall 10' by 18' , with R value from q. 1. Inside temperature is 70 degrees F w

hile outside is 45 degrees F

2 answers:

marissa [1.9K]3 years ago

6 0

Answer:

Just think

Explanation:

gogolik [260]3 years ago

5 0

That is really easy just think about it

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The mechanical energy of an object is a combination of its potential energy and its

saveliy_v [14]

The mechanical energy of an object is a combination of its potential energy and its <em><u>kinetic</u></em><em><u> </u></em><em><u>energy</u></em><em><u>.</u></em>

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2 years ago

Which of these is the BEST description of

strojnjashka [21]

Answer:

i would say C but i may be wrong have a great day

Explanation:

3 0

3 years ago

What is need for using fins?

antiseptic1488 [7]

Answer: It is a term of heat transfer process in which fins are surface that are the extension of the object to work for the heat exchangers to increase the heat exchanging rate.

Explanation: Fins are considered to help the heat exchanger surface to lead the process of heat transfer by increasing the are of the surface which is exposed to the surroundings. Fins work really well with materials having high thermal conductivity and will be more effective. They are preferred because they increase the rate of exchange of heat by increment in the convection.

7 0

3 years ago

In an experiment, the local heat transfer over a flat plate were correlated in the form of local Nusselt number as expressed by

zvonat [6]

Answer:

R= 1.25

Explanation:

As given the local heat transfer,

$Nu_x = 0.035 Re^{0.8}_x Pr^{1/3}$

But we know as well that,

$Nu=\frac{hx}{k}\\h=\frac{Nuk}{x}$

Replacing the values

$h_x=Nu_x \frac{k}{x}\\h_x= 0.035Re^{0.8}_xPr^{1/3} \frac{k}{x}$

Reynolds number is define as,

$Re_x = \frac{Vx}{\upsilon}$

Where V is the velocity of the fluid and \upsilon is the Kinematic viscosity

Then replacing we have

$h_x=0.035(\frac{Vx}{\upsilon})^{0.8}Pr^{1/3}kx^{-1}$

$h_x=0.035(\frac{V}{\upsilon})^{0.8}Pr^{1/3}kx^{0.8-1}$

$h_x=Ax^{-0.2}$

<em>*Note that A is just a 'summary' of all of that constat there.</em>

<em>That is $A=0.035(\frac{V}{\upsilon})^{0.8}Pr^{1/3}k$ </em>

Therefore at x=L the local convection heat transfer coefficient is

$h_{x=L}=AL^{-0.2}$

Definen that we need to find the average convection heat transfer coefficient in the entire plate lenght, so

$h=\frac{1}{L}\int\limit^L_0 h_x dx\\h=\frac{1}{L}\int\limit^L_0 AL^{-0.2}dx\\h=\frac{A}{0.8L}L^{0.8}\\h=1.25AL^{-0.2}$

The ratio of the average heat transfer coefficient over the entire plate to the local convection heat transfer coefficient is

$R = \frac{h}{h_L}\\R= \frac{1.25Al^{-0.2}}{AL^{-0.2}}\\R= 1.25$

3 0

3 years ago

One AA battery in a flashlight stores 9400 J. The three LED flashlight bulbs consume 0.5 W. How many hours will the flashlight l

Effectus [21]

Answer:

time = 5.22 hr

Explanation:

Given data:

Energy of battery = 9400 J

Power consumed by three led bulb is 0.5 watt

we know Power is give as

$Power = \frac{ energy}{time}$

plugging all value and solve for time

$time = \frac{energy}{power}$

$time = \frac{9400}{0.5}$

time = 18,800 sec

in hour

1 hour = 3600 sec

therefore in 18,800 sec

$time = \frac{18800}{3600} = 5.22 hr$

7 0

3 years ago