Please help me with this question

An insulated, vertical piston-cylinder device initially contains 10kg of water, 6kg of which is in the vapor phase. The mass of

Alexeev081 [22]

Answer:

a)120C

b)29kg

Explanation:

Hello!

To solve this exercise follow the steps below

1. we will call 1 the initial state, 2 the steam that enters and 3 the final state

2. We find the quality of the initial state, dividing the mass of steam by the total mass.

$q1=\frac{6kg}{10kg} =0.6$

3 Find the internal energy in the three states using thermodynamic tables

note:Through laboratory tests, thermodynamic tables were developed, these allow to know all the thermodynamic properties of a substance (entropy, enthalpy, pressure, specific volume, internal energy etc ..)

through prior knowledge of two other properties such as pressure and temperature.

u1=IntEnergy(Water;x=0,6(quality);P=200kPa) =1719KJ/kg

u2=IntEnergy(Water;t=350;P=5000kPa) =2808KJ/kg

u3=IntEnergy(Water;x=1;P=200kPa) =2529KJ/kg

4. use the internal energy and pressure to find the temperature in state 3, using thermodynamic tables

T3=Temperature(Water;P=200kPa;u=u3=2529KJ/kg)=120C

5. Use the first law of thermodynamics in the system, it states that the initial energy in a system must be equal to the final

m1u1+m2u2=(m1+m2)u3

where

m1=inital mass=10kg

m2=the mass of the steam that has entered.

solve for m2

(m1)(u1-u3)=(m2)(u3)-(m2)(u2)

$m2=m1\frac{u1-u3}{u3-u2} =10\frac{1719-2529}{2529-2808} =29kg$

7 0

3 years ago

Based on these statements:

Evgen [1.6K]

Answer:

the third statement is true

Explanation:

given data

Lenovos cost more than Dells

Lenovos cost less than Apples

solution

we have given 1st statement that is express as

cost (Lenovo) > cost (Dell) ..................1

and

2nd statement that is express as

cost (Lenovo) < cost (Apple)

so we can say it as

cost (Apple) > cost (Lenovo) ......................2

and

now above Both equation 1 and 2 can be written as

cost (Apple) > cost (Lenovo) > cost (Dell) .........................3

so we can say cost of Apples is more than the cost of Lenovos and the cost of Dells

so as that given 3rd statement is true

7 0

3 years ago

soccer is also called association football" A soccer ball is a sphere, with circumference of 70 centimeters. in developing a new

timama [110]

Answer: Weight on Mars = 0.02593N

Explanation:

Given; Circumference C of Sphere = 70cm = 0.7m,

Specific Gravity S. G. of material = 1.21,

acceleration due to gravity in the Mars gm = 3.7m/s^2

We know that Weight W = mass m × acceleration due to gravity.

Let the Weight in on the Mars be Wm.

Wm = m × gm

Since we are given gm, we need to calculate for m. (Note that mass m is the same everywhere)

But mass = specific gravity × volume

Since we know the specific gravity, let's go ahead to calculate for the volume of the ball.

We know that Volume of a Sphere V = (4/3)πr^3

To get r, we know that C = 2πr

Therefore, r = C/(2π) = 0.7/(2π) = (7/10)/2π = 7/20π (in meters)

V = (4/3)*π×(7/20π)^3 = 343/6000π^2 (in meter^3)

m = 343/6000π^2 × 1.21 = 7.01×10^(-3)kg

Wm = 7.01×10^(-3) × 3.7 = 0.02593N

8 0

3 years ago

You are asked to design a software package for an On-line Banking System (OBS). The OBS will take requests from its user on the

Anit [1.1K]

Answer:

From the statements described above,The proposed software package Online Banking System(OBS) shall provide the following services to the customer(account holder)

Receive all transaction requests from the customers trough online to perform banking activities

Offer a variety of services in banking like:

Opening an account with facilities of Savings,Checking and CD

Issuing checks and check clearance

Transfer of funds between savings and checking account

Establishing a CD(Certificate of Deposit)

Performing routine activities like

Deposit or withdraw funds from a checking account

Closing an account in one of the following operation

Complete closure of account

Closing only savings account

Withdraw CD (on Maturity of CD deposits) and close CD account

Unlike traditional Banking system, OBS offers all the operations through On-line mode over the internet thereby it eliminates manual intervention for the banking transactions from the Bank's side for most of the transactions except some cases like verification of new account applications or complaint redressal and technical support .In such cases ,There will be some users of the software with special privileges to access certain services to perform activities like user data verification and technical support.

Step:1 Identification of actors and software entities for the system to be implemented

The following are the actors identified in the system

Actors:

The users of the proposed system were classified as:

Customer : A user with an active account

Guest user:The user who applies for an account

Administrator:Maintainsand Controls OBS

Manager: Manages the transactions and Banking related issues

Technical Manager: Resolves technical issues of customers

Software entities:

Bank database :Maintains the data of all user accounts

Application server : Maintains the application software components and hosts the OBS website

Automatic Clearing House system : Processes transactions for checks

Step 2: Designing use cases

Use case diagrams are used to describe the system model by representing a set of use cases .Each use case represents a set of actions performed on the system by an actor.

The following are the two approaches of representing the system in a use case model:

1.Representing a use case for actions done by actors e.g. login , logout,message etc.,

2.Representing a use case for business process(Business use cases) e.g. transfer,registration etc.,

The following is the description of five possible business use cases for the requirements specified above

3 0

3 years ago

A converging nozzle has an exit area of 0.001 m2. Air enters the nozzle with negligible velocity at a pressure of 1 MPa and a te

Artyom0805 [142]

Explanation:

a converging nozzle has an exit area of 0.001 m2. Air enters the nozzle with negligible velocity at a pressure of 1 MPa and a temperature of 360 K. For isentropic flow of an ideal gas with k = 1.4 and the gas constant R = Ru/MW = 287 J/kg-K, determine the mass flow rate in kg/s and the exit Mach number for back pressures

100% (3 ratings)

A_2 = 0.001 m^2 P_1 = 1 MPa, T_1 = 360 k P_2 = 500 kpa p^gamma - 1/gamma proportional T (1000/500)^1.4 - 1/1.4 = (360/T_2) 2^4/14 = 360/T_2 T_2

3 0

3 years ago