I need help on this questions they dont give you options soo

2–25 Consider a medium in which the heat conduction equation is given in its simplest form as

barxatty [35]

Answer:

d) Is the thermal conductivity of the medium constant or variable.

Explanation:

As we know that

Heat equation with heat generation at unsteady state and with constant thermal conductivity given as

$\dfrac{d^2T}{dx^2}+\dfrac{d^2T}{dy^2}+\dfrac{d^2T}{dz^2}+\dfrac{\dot{q}_g}{K}=\dfrac{1}{\alpha }\dfrac{dT}{dt}$

With out heat generation

$\dfrac{d^2T}{dx^2}+\dfrac{d^2T}{dy^2}+\dfrac{d^2T}{dz^2}=\dfrac{1}{\alpha }\dfrac{dT}{dt}$

In 2 -D with out heat generation with constant thermal conductivity

$\dfrac{d^2T}{dx^2}+\dfrac{d^2T}{dy^2}=\dfrac{1}{\alpha }\dfrac{dT}{dt}$

Given equation

$\dfrac{d^2T}{dx^2}+\dfrac{d^2T}{dy^2}=\dfrac{1}{a }\dfrac{dT}{dt}$

So we can say that this is the case of with out heat generation ,unsteady state and with constant thermal conductivity.

So the option d is correct.

d) Is the thermal conductivity of the medium constant or variable.

3 0

3 years ago

Two concentric helical compression springs made of steel and having the same length when loaded and when unloaded are used to su

Andrews [41]

Answer:

see explaination for all the answers and full working.

Explanation:

deflection=8P*DN/Gd^4

G(for steel)=70Gpa=70*10^9N/m^2=70KN/mm^2

for outer spring,

deflection=8*3*50^3*5/(70*9^4)=32.66mm

for inner spring

deflection=8*3*30^3*10/(70*5^4)=148.11mm

max stress=k*8*P*C/(3.14*d^2)

for outer spring

c=50/9=5.55

k=(4c-1/4c-4)+.615/c=1.2768

max stress=1.2768*8*3*5.55/(3.14*9^2=.66KN.mm^2

for inner spring

c=6

k=1.2525

max stress=2.29KN/mm^2

6 0

4 years ago

Read 2 more answers

) Please label the following statements as either True (T) or False (F). (a) In general, the greater the % of cold work, the sma

Alexandra [31]

Answer:

A. This option is true

B. This option is false

C. This option is true

Explanation:

A. Generally speaking, the greater percentage of cold, the recrystallization grain size would turn out to be smaller. Therefore this true.

B. A higher annealing temperature does not result in smaller recrystallization grain size. Therefore this is false.

C. As the percentage of cold work is greater, the recrystallization temperature would tend to be lower. Therefore this is true.

6 0

3 years ago

Read Shakespeare's "Sonnet 100.”

liraira [26]

Answer: quatrain

Explanation:

Reading the Shakespeare's "Sonnet 100", we can infer that the underlined section is referred to as a quatrain.

The quatrain simply refers to a type of stanza that is made up of four lines. For example, based on the information given, we can deduce that the rhyme scheme for the second quatrain is given as cdcd.

7 0

3 years ago

Voltage drop testing is being discussed.

Airida [17]

Answer:

Technician B only is correct

Explanation:

Voltage drop testing is a method used to find the amount of electrical resistance available in an high amperage circuit that involves connecting the leads of the meter in parallel to the circuits being tested such that disassembly is not required

In voltage drop test, the red voltmeter lead and black voltmeter lead are placed at two points on the same side of the circuit connection such that the leads are in between two positive connection or two negative connection (rather than connecting the red to the positive and the black to the negative sides of the circuit) and digital voltmeter is used for the voltage drop measurement across the lead while the connection is under load.

Therefore, Technician B only is correct

8 0

3 years ago