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svetoff [14.1K]
3 years ago
8

A heated plate is built into the wall of a large room. The room is maintained at 300 K. The exposed surface of the plate is main

tained at 400 K by a heater attached to the back of the plate. Assume the sides of the plate and back of the heater are perfectly insulated. The exposed surface of the plate (area 0.1 m^2 ) has an emissivity of 0.3 and a convection heat transfer coefficient of 6 W/m^2K with the room and air temperature of 300 K. Show resistance circuit for this problem and draw a picture to show relevant heat modes on system to receive full points. Calculate the following:
a. Find the net radiant heat flux from the plate surface, q1"=____
b. The required heater power, P=______
c. The radiosity of the plate surface, J1=
Engineering
1 answer:
myrzilka [38]3 years ago
7 0

Answer:

B

Explanation:

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Argon is compressed in a polytropic process with n = 1.2 from 100 kPa and 30°C to 1200 kPa in a piston–cylinder device. Determin
gulaghasi [49]

Answer:

<em>181 °C</em>

<em></em>

Explanation:

Initial pressure P_{1} = 100 kPa

Initial temperature T_{1} = 30 °C = 30 + 273 K = 303 K

Final pressure P_{2} = 1200 kPa

Final temperature T_{2} = ?

n = 1.2

For a polytropic process, we use the relationship

(T_{2}/T_{1} ) = (P_{2}/P_{1})^γ

where γ = (n-1)/n

γ = (1.2-1)/1.2 = 0.1667

substituting into the equation, we have

(T_{2}/303) = (1200/100)^0.1667

T_{2}/303 = 12^0.1667

T_{2}/303 = 1.513

T_{2} = 300 x 1.513 = 453.9 K

==> 453.9 - 273 = 180.9 ≅ <em>181 °C</em>

5 0
3 years ago
which of the following tools is used for measuring small diameter holes which a telescoping gauge cannot fit into? A. telescopin
Alex

Answer:

C. Dial indicator

Explanation:

This meassers small diameters

7 0
2 years ago
When cutting a FBD through an axial member, assume that the internal force is tension and draw the force arrow _______ the cut s
shepuryov [24]

Problem-Solving Tip: When cutting an FBD through an axial member, assume that the internal force is tension and draw the force arrow directed away from the cut surface. If the computed internal force value turns out to be a positive number, then the assumption of tension is confirmed.

3 0
2 years ago
What is hardness and how is it generally tested?
drek231 [11]

Answer:

Hardness is understood as the property of materials in general to resist the penetration of an indenter under load, so that the hardness represents the resistance of the material to the plastic deformation located on its surface.

Explanation:

Hardness of a material is understood as the resistance that the material opposes to its permanent surface plastic deformation by scratching or penetration. It is always true that the hardness of a material is inversely proportional to the footprint that remains on its surface when a force is applied.

In this sense, the hardness of a material can also be defined as that property of the surface layer of the material to resist any elastic deformation, plastic or destruction due to the action of local contact forces caused by another body (called indenter or penetrator), harder, of certain shape and dimensions, which does not suffer residual deformations during contact.

That is, hardness is understood as the property of materials in general to resist the penetration of an indenter under load, so that the hardness represents the resistance of the material to the plastic deformation located on its surface.

The following conclusions can be drawn from the previous definition of hardness:  

  1) hardness, by definition, is a property of the surface layer of the material, and is not a property of the material itself;  

  2) the methods of hardness by indentation presuppose the presence of contact efforts, and therefore, the hardness can be quantified within a scale;

  3) In any case, the indenter or penetrator must not undergo residual deformations during the test of hardness measurement of the body being tested.

To determine the hardness of the materials, durometers with different types of tips and ranges of loads are used on the various materials. Below are the most commonly used tests to determine the hardness of the materials.

   Rockwell hardness :

It refers to the Rockwell hardness test, a method with which the hardness or resistance of a material to be penetrated is calculated. It is characterized by being a fast and simple method that can be applied to all types of materials. An optical reader is not required.

    Brinell hardness :

Brinell hardness is a scale that is used to determine the hardness of a material through the indentation method, which consists of penetrating with a hardened steel ball tip into the hard material, a load and for a certain time.  

This test is not very precise but easy to apply. It is one of the oldest and was proposed in 1900 by Johan August Brinell, a Swedish engineer.

    Vickers hardness:

Vickers hardness is a test that is used in all types of solid and thin or soft materials. In this test, a square-shaped pyramid-shaped diamond and a   136° vertex angle are placed on the penetrating equipment.

In this test the hardness measurement is performed by calculating the diagonal penetration lengths.

However, its result is not read directly on the equipment used, therefore, the following formula must be applied to determine the hardness of the material: HV = 1.8544 · F / (dv2).

3 0
3 years ago
1. A _____ is applied to a wall or roof rafters to add strength and keep the building straight and plumb.
PSYCHO15rus [73]

Answer:

A force must s applied to a wall or roof rafters to add strength and keep the building straight and plumb

7 0
2 years ago
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