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Olin [163]
3 years ago
9

Problem 1: Experts on hypothermia tell us that heat loss from the body is much greater in 10°C water than in air at the same tem

perature. To test this, assume that heat transfer from a person can be approximated as that from a vertical cylinder of diameter D = 0.3 m and length L = 1.8 m, with a constant surface temperature of 37°C. Assuming that heat losses from the cylinder occur only at the lateral surfaces, calculate the ratio of the heat transfer rate from the cylinder to water to that for the cylinder to air. Data for the heat transfer properties for water and air can be found in the Appendix in Tables A.2-11 and A.3-3, respectively, and appropriate correlations can be found in eqns (4.7-4), and Tables 4.7-1 and 4.7-2. What do you conclude from this about your odds of survival if you fall into a cold water lake/ocean? (Hint: neglect the cylinder height restriction in Table 4.7-1).

Engineering
1 answer:
pochemuha3 years ago
4 0

Answer:

See explaination

Explanation:

Please see attachment for the step by step solution of the given problem .

It is very detailed in the file attached.

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A ruptured desiccant bag in a reciever-driver is usually caused by what?​
ollegr [7]

Answer: Bad A/C

Explanation: ...

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What is the fastest plane in the world
Aleonysh [2.5K]

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Lockheed SR-71 Blackbird

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7 0
3 years ago
Read 2 more answers
1)What are the three previous manufacturing revolutions Mr. Scalabre mentions? When did these take place?
Ostrovityanka [42]

The three previous manufacturing revolutions that Mr. Scalabre mentioned and their year of occurrence are:

  1. The steam engine in the mid-19th Century
  2. The mass-production model in the early 20th Century
  3. The first automation wave in the 1970s

<h3>What is a Manufacturing Revolution?</h3>

This refers to the process of change from a handicraft economy to industry production-based production.

Hence, we can see that Mr. Scalabre believes we are not growing in productivity because there has not been enough automation to perform the tasks needed.

The effect of robotics is making an impact on productivity because a lot of complex, difficult tasks are done by machines.

3D printing has made an impact on productivity because there is a reduction in the pressing cycle and errors due to negligence are reduced.

The role the engineers have to play in the next revolution is that they would have to produce mathematical model that can be used to produce better AIs

Read more about manufacturing revolutions here:

brainly.com/question/14316656

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8 0
2 years ago
Explain the difference between thermoplastics and thermosets giving structure property correlation.
Misha Larkins [42]

Answer:

Explanation:

Thermosetting polymers are infusible and insoluble polymers. The reason for such behavior is that the chains of these materials form a three-dimensional spatial network, intertwining with strong equivalent bonds. The structure thus formed is a conglomerate of interwoven chains giving the appearance and functioning as a macromolecule, which as the temperature rises, simply the chains are more compacted, making the polymer more resistant to the point where it degrades.

Macromolecules are molecules that have a high molecular mass, formed by a large number of atoms. Generally they can be described as the repetition of one or a few minimum units or monomers, forming the polymers. In contrast, a thermoplastic is a material that at relatively high temperatures, becomes deformable or flexible, melts when heated and hardens in a glass transition state when it cools sufficiently. Most thermoplastics are high molecular weight polymers, which have associated chains through weak Van der Waals forces (polyethylene); strong dipole-dipole and hydrogen bond interactions, or even stacked aromatic rings (polystyrene). Thermoplastic polymers differ from thermosetting polymers or thermofixes in that after heating and molding they can overheat and form other objects.

Thermosetting plastics have some advantageous properties over thermoplastics. For example, better resistance to impact, solvents, gas permeation and extreme temperatures. Among the disadvantages are, generally, the difficulty of processing, the need for curing, the brittle nature of the material (fragile) and the lack of reinforcement when subjected to tension. But even so in many ways it surpasses the thermoplastic.

The physical properties of thermoplastics gradually change if they are melted and molded several times (thermal history), these properties are generally diminished by weakening the bonds. The most commonly used are polyethylene (PE), polypropylene (PP), polybutylene (PB), polystyrene (PS), polymethylmethacrylate (PMMA), polyvinylchloride (PVC), ethylene polyterephthalate (PET), Teflon (or polytetrafluoroethylene, PTFE) and nylon (a type of polyamide).

They differ from thermosets or thermofixes (bakelite, vulcanized rubber) in that the latter do not melt when raised at high temperatures, but burn, making it impossible to reshape them.

Many of the known thermoplastics can be the result of the sum of several polymers, such as vinyl, which is a mixture of polyethylene and polypropylene.

When they are cooled, starting from the liquid state and depending on the temperatures to which they are exposed during the solidification process (increase or decrease), solid crystalline or non-crystalline structures may be formed.

This type of polymer is characterized by its structure. It is formed by hydrocarbon chains, like most polymers, and specifically we find linear or branched chains

4 0
3 years ago
For a steel alloy it has been determined that a carburizing heat treatment of 11-h duration will raise the carbon concentration
Jobisdone [24]

Answer:

Time =t2=58.4 h

Explanation:

Since temperature is the same hence using condition

x^2/Dt=constant

where t is the time as temperature so D also remains constant

hence

x^2/t=constant

2.3^2/11=5.3^2/t2

time=t^2=58.4 h

4 0
3 years ago
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