1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
lisov135 [29]
2 years ago
11

A gas expands in a piston-cylinder assembly from p1 = 8 bar, V1 = 0.02 m3 to p2 = 2 bar. The relation between pressure and volum

e during the gas expansion process is pV1.2 = constant. The mass of the gas is 0.25 kg. If the specific internal energy of the gas decreases by 55 kJ/kg during the process, determine the heat transfer, in kJ. Kinetic and potential energy effects are negligible.
Engineering
1 answer:
Charra [1.4K]2 years ago
7 0

Answer:

The heat transfer is 29.75 kJ

Explanation:

The process is a polytropic expansion process

General polytropic expansion process is given by PV^n = constant

Comparing PV^n = constant with PV^1.2 = constant

n = 1.2

(V2/V1)^n = P1/P2

(V2/0.02)^1.2 = 8/2

V2/0.02 = 4^(1/1.2)

V2 = 0.02 × 3.2 = 0.064 m^3

W = (P2V2 - P1V1)/1-n

P1 = 8 bar = 8×100 = 800 kPa

P2 = 2 bar = 2×100 = 200 kPa

V1 = 0.02 m^3

V2 = 0.064 m^3

1 - n = 1 - 1.2 = -0.2

W = (200×0.064 - 800×0.02)/-0.2 = -3.2/-0.2 = 16 kJ

∆U = 55 kJ/kg × 0.25 kg = 13.75 kJ

Heat transfer (Q) = ∆U + W = 13.75 + 16 = 29.75 kJ

You might be interested in
1. Springs____________<br> energy when compressed<br> And _________energy when they rebound.
densk [106]

Answer:

Springs store energy when compressed and release energy when they rebound

Explanation:

6 0
2 years ago
A machine raises 20kg of water through a height of 50m in 10secs. What is the power of the machine.​
Tomtit [17]

Answer:

hhahhhwghwhwhwhwjwnwjnnnnwnwwnw

Explanation:

jwkwkkwoiwiwiwiwiwowwiwowowiiiiwuuwuwgeevehehsvhsvwhbhhehehwgjjwhwhjwjqwjjuuuwi####!\\\\e

5 0
2 years ago
HELP<br><br><br>the overall width of a part is dimensioned as 3.00 ± 0.02. what is the tolerance
MariettaO [177]

Answer:

Not knowing the units the tolerance is 0.02.  I would presume mm but hopefully your question has more detail.  

Explanation:

The tolerance is the portion after the main dimension (+/- 0.02).  In our case we have bilateral tolerance since there is tolerance in both directions (positive and negative).  If you were building a part the acceptable range would be 2.98 to 3.02 based on the tolerance provided.  

3 0
3 years ago
Read 2 more answers
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
2 years ago
Adding new equipment or processes may require changes to the PPE requirements for
Yuki888 [10]
I think it’s is false I’m not that sure
5 0
2 years ago
Read 2 more answers
Other questions:
  • A slight breeze is blowing over the hot tub above and yields a heat transfer coefficient h of 20 W/m2 -K. The air temperature is
    15·1 answer
  • white Sands national monument is a large area made of white sand dunes. what is likely to be true of this area?​
    8·1 answer
  • The news media often report an earthquake's magnitude on the Richter scale. Which of the following items are characteristics of
    14·1 answer
  • All sized companies are required to have a written fire prevention plan true or false
    14·2 answers
  • Problem 89:A given load is driven by a 480 V six-pole 150 hp three-phase synchronous motor with the following load and motor dat
    11·1 answer
  • Find the dryness fraction, specific volume and internal energy of steam at 7bar nd enthalpy 2600kj/kh. (0.921,0.2515m³/kg , 2420
    5·1 answer
  • Technician A says when you push the horn button, electromagnetism moves an iron bar inside the horn, which opens and closes cont
    5·2 answers
  • A demand factor of _____ percent applies to a multifamily dwelling with ten units if the optional calculation method is used.
    14·1 answer
  • An engine has been diagnosed with blowby.
    12·1 answer
  • Why do some ladders have a white tip or reflective tape attached to the tip?
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!