The attached program (studentsGpa.cpp) uses dynamic allocation to create an array of strings. It asks the user to enter a number and based on the entered number it allocates the array size. Then based on that number it asks the user that many times to enter student’s names. What you need to do:Add another array of doubles to store the gpa of each student as you enter themYou need to display both the student’s name and the gpa.NOTE: must use pointer notation not array subscript. Any submission that uses array subscript won’t be graded
Answers
Question: The program was not attached to your question. Find attached of the program and the answer.
Answer:
See the explanation for the answer.
Explanation:
#include <iostream>
using namespace std;
int main()
{
cout << "How many students will you enter? ";
int n;
cin>>n;
string *name = new string[n];
double *gpa = new double[n];
for(int i=0;i<n;i++){
cout<<"Enter student"<<(i+1)<<"'s name: ";
cin>>name[i];
cout<<"Enter student"<<(i+1)<<"'s gpa: ";
cin>>gpa[i];
}
cout<<"The list students"<<endl;
cout<<"Name GPA"<<endl;
cout<<"----------------------"<<endl;
for(int i=0;i<n;i++){
cout<<name[i]<<" "<<gpa[i]<<endl;
}
return 0;
}
OUTPUT : See the attached file.
Related Questions
Compute the acceleration of gravity for a given distance from the earth's center, distCenter, assigning the result to accelGravity. The expression for the acceleration of gravity is: (G * M) / (d2), where G is the gravitational constant 6.673 x 10-11, M is the mass of the earth 5.98 x 1024 (in kg) and d is the distance in meters from the earth's center (stored in variable distCenter).Sample program:#include int main(void) { const double G = 6.673e-11; const double M = 5.98e24; double accelGravity = 0.0; double distCenter = 0.0; distCenter = 6.38e6; printf("accelGravity: %lf\n", accelGravity); return 0;
Answers
Answer:
See Explaination
Explanation:
#include <stdio.h>
int main(void)
{
const double G = 6.673e-11;
const double M = 5.98e24;
double accelGravity = 0.0;
double distCenter = 0.0;
distCenter = 6.38e6;
//<StudentCode>
accelGravity = (G * M) / (distCenter * distCenter);
printf("accelGravity: %lf\n", accelGravity);
return 0;
}
Water is flowing in a pipe. Which is the correct statement about the effect of an increase in the Reynolds number of the flow:
a.if the flow is laminar it cannot become turbulent if the wall is smooth.
b.if the flow is turbulent it could become laminar.
c.if the flow is laminar it could become turbulent.
d.if the flow is laminar it cannot become turbulent unless the wall is rough.
Answers
Answer:
c.if the flow is laminar it could become turbulent.
Explanation:
The Reynolds number (Re) is a dimensionless quantity used to help predict flow patterns in different fluid flow situations. At low Reynolds numbers of below 2300 flows tend to be dominated by laminar, while at high Reynolds numbers above 4000, turbulence results from differences in the fluid's speed and direction. In between these values is the transition region of flow.
In practice, fluid flow is generally chaotic, and very small changes to shape and surface roughness of bounding surfaces can result in very different flows.
A silicon pn junction diode at t has a cross sectional area of cm the length of the p region is and the length of the n region is the doping concentrations are determine approximately the series resistance of the diode and the current through the diode that will produce a drop across this series resistance.
Answers
Answer:
Explanation:
r=72.3 is my thought
I hope it is helpful
Traditional password entry schemes are susceptible to "shoulder surfing" in which an attacker watches an unsuspecting user enter their password or PIN number and uses it later to gain access to the account. One way to combat this problem is with a randomized challenge-response system. In these systems, the user enters different information every time based on a secret in response to a randomly generated challenge. Consider the fol- lowing scheme in which the password consists of a five-digit PIN number (00000 to 99999). Each digit is assigned a random number that is 1, 2, or 3. The user enters the random numbers that correspond to their PIN instead of their actual PIN numbers.For example, consider an actual PIN number of 12345. To authenticate the user would be presented with a screen such as:PIN: 0 1 2 3 4 5 6 7 8 9 NUM: 3 2 3 1 1 3 2 2 1 3The user would enter 23113 instead of 12345. This doesn’t divulge the password even if an attacker intercepts the entry because 23113 could correspond to other PIN numbers, such as 69440 or 70439. The next time the user logs in, a different sequence of random numbers would be generated, such as: PIN: 0 1 2 3 4 5 6 7 8 9 NUM: 1 1 2 3 1 2 2 3 3 3Your program should simulate the authentication process. Store an actual PIN number in your program. The program should use an array to assign random numbers to the digits from 0 to 9. Output the random digits to the screen, input the response from the user, and output whether or not the user’s response correctly matches the PIN number.I have this code so far, but would like to input cstrings and vectors to fulfill the requirements, I need help with that. This is for c++ for beginners#include #include #include #include using namespace std;void generateRandomNumbers(int *random){ // Use current time as seed for random generatorsrand(time(0));for(int i=0;i<10;i++){random[i] = 1 + rand() % 3;}}bool isMatch(string pin,string randomPin,int *random){int index;for(int i=0;i<(int)pin.length();i++){ //converting pin number to int so that we can check the random number at that indexindex = pin[i]-'0';if((randomPin[i]-'0') != random[index-1])return false;}return true;}int main(){string pin = "12345";string randomPin;int random[10];generateRandomNumbers(random);cout << "Randomly Generated numbers " << endl;for(int i=0;i<10;i++){cout << random[i] << " ";}cout << endl;cout << "Now Enter your pin interms of random numbers: ";cin >> randomPin;if(isMatch(pin,randomPin,random)){cout << "Both matches" << endl;}else{cout << "Sorry you entered wrong pin.." << endl;}}
Answers
The following code or the program will be used:
Explanation:
import java.util.Scanner;
public class Authenticate
{
public static void main(String[] args)
{
// Actual password is 99508
int[] actual_password = {9, 9, 5, 0, 8};
// Array to hold randomly generated digits
int[] random_nums = new int[10];
// Array to hold the digits entered by the user to authenticate
int[] entered_digits = new int[actual_password.length];
// Randomly generate numbers from 1-3 for
// for each digit
for (int i=0; i < 10; i++)
{
random_nums[i] = (int) (Math.random() * 3) + 1;
}
// Output the challenge
System.out.println("Welcome! To log in, enter the random digits from 1-3 that");
System.out.println("correspond to your PIN number.");
System.out.println();
System.out.println("PIN digit: 0 1 2 3 4 5 6 7 8 9");
System.out.print("Random #: ");
for (int i=0; i<10; i++)
{
System.out.print(random_nums[i] + " ");
}
System.out.println();
System.out.println();
// Input the user's entry
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter code.");
String s = keyboard.next();
String s = keyboard.next();
// Extract the digits from the code and store in the entered_digits array
for (int i=0; i<s.length(); i++)
{
entered_digits[i] = s.charAt(i) - '0'; // Convert char to corresponding digit
}
// At this point, if the user typed 12443 then
// entered_digits[0] = 1, entered_digits[1] = 2, entered_digits[2] = 4,
// entered_digits[3] = 4, and entered_digits[4] = 3
/****
TO DO: fill in the parenthesis for the if statement
so the isValid method is invoked, sending in the arrays
actual_password, entered_digits, and random_nums as
parameters
***/
if (isValid (actual_password, entered_digits, random_nums)) // FILL IN HERE
{
System.out.println("Correct! You may now proceed.");
}
else
{
System.out.println("Error, invalid password entered.");
}
/***
TO DO: Fill in the body of this method so it returns true
if a valid password response is entered, and false otherwise.
For example, if:
actual = {9,9,5,0,8}
randnums = {1,2,3,1,2,3,1,2,3,1}
then this should return true if:
entered[0] == 1 (actual[0] = 9 -> randnums[9] -> 1)
entered[1] == 1 (actual[1] = 9 -> randnums[9] -> 1)
entered[2] == 3 (actual[2] = 5 -> randnums[5] -> 3)
entered[3] == 1 (actual[3] = 0 -> randnums[0] -> 1)
entered[4] == 3 (actual[4] = 8 -> randnums[8] -> 3)
or in other words, the method should return false if any of
the above are not equal.
****/
public static boolean isValid(int[] actual, int[] entered, int[] randnums)
{
int Index = 0;
boolean Valid = true;
while (Valid && (Index < actual.length))
{
int Code = actual[Index];
if (entered [Index] != randnums [Code])
{
Valid = false;
}
Index++;
}
return Valid;
}
Given an unsorted array of distinct positive integers A[1..n] in the range between 1 and 10000 and an integer i in the same range. Here n can be arbitrary large. You want to find out whether there are 2 elements of the array that add up to i. Give an algorithm that runs in time O(n).
Answers
Answer:
Explanation:
Arbitrary means That no restrictions where placed on the number rather still each number is finite and has finite length. For the answer to the question--
Find(A,n,i)
for j =0 to 10000 do
frequency[j]=0
for j=1 to n do
frequency[A[j]]= frequency[A[j]]+1
for j =1 to n do
if i>=A[j] then
if (i-A[j])!=A[j] and frequency[i-A[j]]>0 then
return true
else if (i-A[j])==A[j] and frequency[j-A[j]]>1 then
return true
else
if (A[j]-i)!=A[j] and frequency[A[j]-i]>0 then
return true
else if (A[j]-i)==A[j] and frequency[A[j]-i]>1 then
return true
return false
A 50-lbm iron casting, initially at 700o F, is quenched in a tank filled with 2121 lbm of oil, initially at 80o F. The iron casting and oil can be modeled as incompressible with specific heats 0.10 Btu/lbm o R, and 0.45 Btu/lbm o R, respectively. For the iron casting and oil as the system, determine: a) The final equilibrium temperature (o F) b) The total entropy change for this process (Btu/ o R) (Hint: Total entropy change is the sum of entropy change of iron casting and oil.)
Answers
Answer:
a) The final equilibrium temperature is 83.23°F
b) The entropy production within the system is 1.9 Btu/°R
Explanation:
See attached workings
a) Equilibrium temp. ≈ 77.01°F.
b) Total entropy change ≈ 104.58 Btu/°R.
To solve this problem, we can apply the principle of energy conservation and the definition of entropy change.
a) The final equilibrium temperature can be found using the principle of energy conservation, which states that the heat lost by the hot object (iron casting) equals the heat gained by the cold object (oil) during the process.
The equation for energy conservation is:
[tex]\[ m_{\text{iron}} \times C_{\text{iron}} \times (T_{\text{final}} - T_{\text{initial, iron}}) = m_{\text{oil}} \times C_{\text{oil}} \times (T_{\text{final}} - T_{\text{initial, oil}}) \][/tex]
Where:
- [tex]\( m_{\text{iron}} \)[/tex] = mass of iron casting = 50 lbm
- [tex]\( C_{\text{iron}} \)[/tex] = specific heat of iron casting = 0.10 Btu/lbm °R
- [tex]\( T_{\text{initial, iron}} \)[/tex] = initial temperature of iron casting = 700 °F
- [tex]\( m_{\text{oil}} \)[/tex] = mass of oil = 2121 lbm
- [tex]\( C_{\text{oil}} \)[/tex] = specific heat of oil = 0.45 Btu/lbm °R
- [tex]\( T_{\text{initial, oil}} \)[/tex] = initial temperature of oil = 80 °F
- [tex]\( T_{\text{final}} \)[/tex] = final equilibrium temperature (unknown)
Now, let's solve for [tex]\( T_{\text{final}} \)[/tex]:
[tex]\[ 50 \times 0.10 \times (T_{\text{final}} - 700) = 2121 \times 0.45 \times (T_{\text{final}} - 80) \][/tex]
[tex]\[ 5(T_{\text{final}} - 700) = 954.45(T_{\text{final}} - 80) \][/tex]
[tex]\[ 5T_{\text{final}} - 3500 = 954.45T_{\text{final}} - 76356 \][/tex]
[tex]\[ 0 = 949.45T_{\text{final}} - 72856 \][/tex]
[tex]\[ T_{\text{final}} = \frac{72856}{949.45} \][/tex]
[tex]\[ T_{\text{final}} \approx 77.01 \, ^\circ F \][/tex]
So, the final equilibrium temperature is approximately [tex]\( 77.01 \, ^\circ F \).[/tex]
b) The total entropy change for the process can be calculated using the formula:
[tex]\[ \Delta S = \Delta S_{\text{iron}} + \Delta S_{\text{oil}} \][/tex]
Where:
- [tex]\( \Delta S_{\text{iron}} = \frac{Q_{\text{iron}}}{T_{\text{initial, iron}}} \)[/tex]
- [tex]\( \Delta S_{\text{oil}} = \frac{Q_{\text{oil}}}{T_{\text{initial, oil}}} \)[/tex]
- [tex]\( Q_{\text{iron}} \) = heat lost by the iron casting[/tex]
- [tex]\( Q_{\text{oil}} \) = heat gained by the oil[/tex]
Let's calculate:
[tex]\[ Q_{\text{iron}} = m_{\text{iron}} \times C_{\text{iron}} \times (T_{\text{final}} - T_{\text{initial, iron}}) \][/tex]
[tex]\[ Q_{\text{iron}} = 50 \times 0.10 \times (77.01 - 700) \][/tex]
[tex]\[ Q_{\text{iron}} \approx -3175.495 \, \text{Btu} \][/tex]
[tex]\[ Q_{\text{oil}} = m_{\text{oil}} \times C_{\text{oil}} \times (T_{\text{final}} - T_{\text{initial, oil}}) \][/tex]
[tex]\[ Q_{\text{oil}} = 2121 \times 0.45 \times (77.01 - 80) \][/tex]
[tex]\[ Q_{\text{oil}} \approx 8729.535 \, \text{Btu} \][/tex]
Now, calculate entropy changes:
[tex]\[ \Delta S_{\text{iron}} = \frac{-3175.495}{700} \][/tex]
[tex]\[ \Delta S_{\text{iron}} \approx -4.5364 \, \text{Btu/°R} \][/tex]
[tex]\[ \Delta S_{\text{oil}} = \frac{8729.535}{80} \][/tex]
[tex]\[ \Delta S_{\text{oil}} \approx 109.118 \, \text{Btu/°R} \][/tex]
[tex]\[ \Delta S = -4.5364 + 109.118 \][/tex]
[tex]\[ \Delta S \approx 104.5816 \, \text{Btu/°R} \][/tex]
So, the total entropy change for this process is approximately [tex]\( 104.5816 \, \text{Btu/°R} \).[/tex]
Amplifiers are extensively used in the baseband portion of a radio receiver system to condition the baseband signal to produce an output signal ready for digital sampling and storage. Some of the key design features of baseband amplifiers include
i. DC gain,
ii. output swing,
iii. power consumption, and
iv. bandwidth.
Answers
Answer:
Please see the attached file for the complete answer.
Explanation:
simply supported beam is subjected to a linearly varying distributed load ( ) 0 q x x L 5 q with maximum intensity 0 q at B. The beam has a length L 5 4 m and rectangular cross section with a width of 200 mm and height of 300 mm. Determine the maximum permissible value for the maximum inten- sity, 0 q , if the allowable normal stresses in tension and compression are 120 MPa.
Answers
Answer:
q₀ = 350,740.2885 N/m
Explanation:
Given
[tex]q(x)=\frac{x}{L} q_{0}[/tex]
σ = 120 MPa = 120*10⁶ Pa
[tex]L=4 m\\w=200 mm=0.2m\\h=300 mm=0.3m\\q_{0}=? \\[/tex]
We can see the pic shown in order to understand the question.
We apply
∑MB = 0 (Counterclockwise is the positive rotation direction)
⇒ - Av*L + (q₀*L/2)*(L/3) = 0
⇒ Av = q₀*L/6 (↑)
Then, we apply
[tex]v(x)=\int\limits^L_0 {q(x)} \, dx\\v(x)=-\frac{q_{0}}{2L} x^{2}+\frac{q_{0} L}{6} \\M(x)=\int\limits^L_0 {v(x)} \, dx=-\frac{q_{0}}{6L} x^{3}+\frac{q_{0} L}{6}x[/tex]
Then, we can get the maximum bending moment as follows
[tex]M'(x)=0\\ (-\frac{q_{0}}{6L} x^{3}+\frac{q_{0} L}{6}x)'=0\\ -\frac{q_{0}}{2L} x^{2}+\frac{q_{0} L}{6}=0\\x^{2} =\frac{L^{2}}{3}\\ x=\sqrt{\frac{L^{2}}{3}} =\frac{L}{\sqrt{3} }=\frac{4}{\sqrt{3} }m[/tex]
then we get
[tex]M(\frac{4}{\sqrt{3} })=-\frac{q_{0}}{6*4} (\frac{4}{\sqrt{3} })^{3}+\frac{q_{0} *4}{6}(\frac{4}{\sqrt{3} })\\ M(\frac{4}{\sqrt{3} })=-\frac{8}{9\sqrt{3} } q_{0} +\frac{8}{3\sqrt{3} } q_{0}=\frac{16}{9\sqrt{3} } q_{0}m^{2}[/tex]
We get the inertia as follows
[tex]I=\frac{w*h^{3} }{12} \\ I=\frac{0.2m*(0.3m)^{3} }{12}=4.5*10^{-4}m^{4}[/tex]
We use the formula
σ = M*y/I
⇒ M = σ*I/y
where
[tex]y=\frac{h}{2} =\frac{0.3m}{2}=0.15m[/tex]
If M = Mmax, we have
[tex](\frac{16}{9\sqrt{3} }m^{2} ) q_{0}\leq \frac{120*10^{6}Pa*4.5*10^{-4}m^{4} }{0.15m}\\ q_{0}\leq 350,740.2885\frac{N}{m}[/tex]
Water in a household plumbing system originates at the neighborhood water main where the pressure is 480 kPa, the velocity is 5 m/s, and the elevation is 2.44 m. A 19-mm (3/4-in) copper service line supplies water to a two-story residence where the faucet in the master bedroom is 40 m (of pipe) away from the main and at an elevation of 7.62 m. If the sum of the minor-loss coefficients is 3.5, estimate the maximum (open faucet) flow. How would this flow be affected by the operation of other faucets in the house?
Answers
Answer:
1. Maximum flow = 0.7768 L/s
2. The flow would reduced if other faucets were open. This is due to increase pipe flow and frictional resistance between the water main and the faucets.
Explanation:
See the attached file for the calculation.
A certain well-graded sand deposit has an in-situ relative density of about 50%. A laboratory strength test on a sample of this soil produced an effective friction angle of 31. Does this test result seem reasonable? Explain the basis for your response.
Answers
Answer:
The result seem reasonable.
Explanation:
Relative density shows us how heavy a substance is in comparison to water.It aids us in determine the density of an unknown substance by knowing the density of a known substance. Relative density is defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. It is very important in the accurate determination of density.
Relative density= emax - e/emax - emin× 100
Relative density ranges between 35 and 65 because the soil is in medium state.
For well graveled sand, maximum friction angle is uo^r
and for minimum friction angle, minimum friction angle is 33°.
Therefore, for given friction angle of 31° (shear strength criteria). This result seem reasonable.
Therefore, it is worthy to note that if friction angle is more, the shear strength is more which implies that it is a densified soil, that is to say, void ratio decreases.
Go online and search for information about companies that have been harmed or bankrupted by a disaster. Choose one such company and create a brief case study about it. Successful narratives will focus on the manner in which the organization was impacted, including financial losses, losses of sales, or the need for layoffs.
Answers
Answer:
See explaination
Explanation:
In recent times and in the past, so many companies have been dealt with or bankrupted by disaster.
This disasters are in the form of floods, earthquake and tsunami. This has led to many companies across world to have faced problem. As Japan is particularly vulnerable to natural disaster because of its climate and topography let me take example of japan .The tsunami that struck Japan in March this year which has lead to a debt of worth nearly $8 billion due to failed businesses. A total of 341 firms in japan with a combined 6,376 employees has got affected by this disaster.
One of company that hit hard by these disaster is Toyota. Toyota is a Japanese multinational automotive manufacturer headquartered in Toyota, Aichi, Japan. Actually due to flood in thailand toyota has faced a big loss. As flood hit thailand the parts of vehicle which is produced in thailand has stopped . It leads to interruption in the supply chain of some Thailand made components.
This lead to suspension of production as thai made component was unavailable.It has been reported until the situation of thailand will be good toyota plants in Indiana, Kentucky and Ontario, Canada, will be shut down . And production rate at plant in North America will get slow down .This flood leads to a loss of 37500 vehicles .Due to this reason toyota was forced to open its plants in Southeast asian country just to enhance the production rate.Sales of vehicle has also got reduced in thailand . Hence toyota faced a total loss of 1.6 billion dollar.
In Nigeria, due to the insurgency of the Boko Haram, many companies have entirely stopped operations in some regions, this harsh realities leads to massive loss of revenue for such companies.
Air at T1 = 32°C, p1 = 1 bar, 50% relative humidity enters an insulated chamber operating at steady state with a mass flow rate of 3 kg/min and mixes with a saturated moist air stream entering at T2 = 7°C, p2 = 1 bar. A single mixed stream exits at T3 = 17°C, p3 = 1 bar. Neglect kinetic and potential energy effects
Determine
(a) the relative humidity and temperature, in °C, of the exiting stream.
Answers
To determine the relative humidity of the mixed air stream based on the information provided, one would typically use a psychrometric chart or other moist air property calculations. Without access to the required psychrometric data or tables to reference, an accurate calculation cannot be provided here, but principles of moist air mixing and conservation of mass for the water vapor can guide the process.
Explanation:To determine the relative humidity and temperature of the exiting stream in the mixing chamber problem, we need to use the principles of thermodynamics specifically relating to moist air properties. This requires using a psychrometric chart or similar calculation methods to find the properties of the mixed air stream. The information provided in the initial question about the temperatures, pressures, and humidities of the incoming air streams is used along with conservation of mass and energy principles.
However, as a tutor on Brainly, I do not have access to the necessary tables or psychrometric data through this platform, which are required to calculate the final relative humidity of the exiting stream. Such data typically includes saturation pressure, saturation temperature, and specific enthalpy of the air-water mixture at various conditions.
To solve the problem accurately, you would need to reference the appropriate psychrometric chart or software at the specific temperatures given in the question. Assuming the total pressure remains constant and using the principle of the conservation of mass for the water vapor, the mixing ratio of the incoming streams can be used to determine the mixing ratio of the outgoing stream. Then, with the final temperature known, you could identify the corresponding saturation mixing ratio and use it to calculate the relative humidity.
If we assume that the mass flow rates of both streams are equal, we can consider that the exiting air stream will be a mixture of the two streams. Given the final exit temperature of 17°C, we could interpolate between the saturation mixing ratios at the temperatures given for the two streams to estimate the relative humidity, but a more precise result would come from detailed calculations or a psychrometric chart.
From the following numbered list of characteristics, decide which pertain to (a) precipitation hardening, and which are displayed by (b) dispersion strengthening. (1) The strengthening mechanism involves the hindering of dislocation motion by precipitates/particles. (2) The hardening/strengthening effect is not retained at elevated temperatures for this process (3) The hardening/strengthening effect is retained at elevated temperatures for this process (4) The strength is developed by a heat treatment (5) The strength is developed without a heat treatment
Answers
Answer:
(a) Precipitation hardening
(1) The strengthening mechanism involves the hindering of dislocation motion by precipitates/particles.
(2) The hardening/strengthening effect is not retained at elevated temperatures for this process.
(4) The strength is developed by a heat treatment.
(b) Dispersion strengthening
(1) The strengthening mechanism involves the hindering of dislocation motion by precipitates/particles.
(3) The hardening/strengthening effect is retained at elevated temperatures for this process.
(5) The strength is developed without a heat treatment.
The size of an engine is called the engine
A. bore.
B. stroke.
C. displacement.
D. mass.
Answers
a hollow shaft is required to transmit 600kw at 110 rpm, the maximum torque being 20% greater than the mean. the shear stress is not to exceed 63 mpa and twist in a length of 3 meters not t exeed 1.4 degrees Calculate the minimum external diameter satisfying these conditions.
Answers
Answer:
175.5 mm
Explanation:
a hollow shaft of diameter ratio 3/8 is required to transmit 600kw at 110 rpm, the maximum torque being 20% greater than the mean. the shear stress is not to exceed 63 mpa and twist in a length of 3 meters not t exeed 1.4 degrees Calculate the minimum external diameter satisfying these conditions. G = 80 GPa
Let
D = external diameter of shaft
Given that:
d = internal diameter of the shaft = 3/8 × D = 0.375D,
Power (P) = 600 Kw, Speed (N) = 110 rpm, Shear stress (τ) = 63 MPa = 63 × 10⁶ Pa, Angle of twist (θ) = 1.4⁰, length (l) = 3 m, G = 80 GPa = 80 × 10⁹ Pa
The torque (T) is given by the equation:
[tex]T=\frac{60 *P}{2\pi N}\\ Substituting:\\T=\frac{60*600*10^3}{2\pi*110} =52087Nm[/tex]
The maximum torque ([tex]T_{max[/tex]) = 1.2T = 1.2 × 52087 =62504 Nm
Using Torsion equation:
[tex]\frac{T}{J} =\frac{\tau}{R}\\ J=\frac{T.R}{\tau} \\\frac{\pi}{32}[D^4-(0.375D)^4]=\frac{62504*D}{2(63*10^6)} \\D^3(0.9473)=0.00505\\D=0.1727m=172.7mm[/tex]
[tex]\theta=1.4^0=\frac{1.4*\pi}{180}rad[/tex]
From the torsion equation:
[tex]\frac{T}{J} =\frac{G\theta }{l}\\ J=\frac{T.l}{G\theta} \\\frac{\pi}{32}[D^4-(0.375D)^4]=\frac{62504*3}{84*10^9*\frac{1.4*\pi}{180} } \\D=0.1755m=175.5mm[/tex]
The conditions would be satisfied if the external diameter is 175.5 mm
1. A four-lane freeway (two lanes in each direction) is located on rolling terrain and has 12-ft lanes, no lateral obstructions within 6 ft of the pavement edges, and there are two ramps within three miles upstream of the segment midpoint and three ramps within three miles downstream of the segment midpoint. A weekday directional peak-hour volume of 1800 vehicles (familiar users) is observed, with 700 arriving in the most congested 15-min period. If a LOS no worse than C is desired, determine the maximum number of heavy vehicles that can be present in the peak-hour traffic stream.
Answers
Answer:
Maximum number of vehicle = 308
Explanation:
See the attached file for the calculation.
Refrigerant 134a is the working fluid in a vaporcompression heat pump that provides 35 kW to heat a dwelling on a day when the outside temperature is below freezing. Saturated vapor enters the compressor at 1.6 bar, and saturated liquid exits the condenser, which operates at 8 bar. Determine for isentropic compression a. the refrigerant mass flow rate, in kg/s. b. the compressor power, in kW. c. the coefficient of performance. Recalculate the quantities in parts (b) and (c) for an isentropic compressor efficiency of 75%.
Answers
Thermodynamic calculations for mass flow rate, compressor power, and coefficient of performance of a heat pump require refrigerant property data, which is not provided in the question. An energy balance and compressor efficiency adjustment are also essential for accurate calculations.
Explanation:To calculate the properties of the heat pump using refrigerant 134a and determine the refrigerant mass flow rate, compressor power, and coefficient of performance, we need to make use of thermodynamic equations and refrigerant property data under the given conditions (such as pressures and phase states).Normally, these calculations would involve using a thermodynamic properties table or software to find enthalpies for the refrigerant at the specified conditions. An energy balance would be applied around the compressor and condenser. The work done by the compressor can be calculated using the enthalpy values before and after the compressor and assuming an isentropic process initially, and then adjusting for the non-ideal compressor efficiency of 75% in the revised calculation.For the coefficient of performance (COP) of the heat pump, it is calculated as the ratio of heat output to work input for the heating mode. The provided heat output is given here as 35 kW. For ideal conditions, the COP can be calculated without the compressor efficiency factor; for the revised COP with a 75% efficient compressor, this factor is taken into account.Unfortunately, without the enthalpy values or additional data, it is not possible to provide the numerical answers to the student's question.
consider a household that uses 23.8 kw-hour of electricity per day on average. (kw-hours is a measure of energy that will be discussed in detail in a later chapter. at this point we want to establish estimations.) most of that electricity is supplied by fossil fuels. to reduce their carbon footprint, the household wants to install solar panels, which receive on average 336 w/m2 from the sun each day. if the solar panels are 19.0% efficient (fraction of solar energy converted into useable electrical energy), what area of solar panels is needed to power the household
Answers
Answer:
15.53 m2
Explanation:
Energy needed = 23.8 kW-hr
Solar intensity of required panel = 336 W/m2
Efficiency of panels = 19%
Power needed = 23.8kW-hr = 23800 W-h,
In one day there are 24 hr, therefore power required = 23800/24 = 991.67 W
991.67 = 19% of incident power
991.67 = 0.19x
x = incident power = 991.67/0.19 = 5219.32 W
Surface area required = 5219.32/336
= 15.53 m2
Alloy parts were cast with a sand mold that took 160 secs for a cube-shaped casting to solidify. The cube was 50 mm on a side. (a) Determine the value of the Chvorinov's mold constant. (b) If the same alloy and mold type were used, find the total solidification time for a cylindrical casting in which the diameter = 25 mm and length = 50 mm.
Answers
Answer:
a) k = 6.4 s/cm²
b) Te = 160 s
Explanation:
a) Given
Solidification time in s: Te = 160 s
L = 50 mm = 5 cm
We use the formula
Te = k*(V/A)ⁿ
k = Te*(A/V)ⁿ
where
k is the Chvorinov's mold constant
V is casting volume in cm³ = V = L³ = (5 cm)³ = 125 cm³
A is the surface area of the casting in cm² = A = L² = (5 cm)² = 25 cm²
n = 2 (assumed)
⇒ k = 160 s*(25 cm²/125 cm³)²
⇒ k = 6.4 s/cm²
b) Given
D = 25 mm = 2.5 cm ⇒ R = D/2 = 2.5 cm/2 = 1.25 cm
h = 50 mm = 5 cm
k = 6.4 s/cm²
n = 2
We find the volume as follows
V = π*R²*h ⇒ V = π*(1.25 cm)²*(5 cm) = 24.5436 cm³
and the surface area
A = π*R² = π*(1.25 cm)² = 4.9087 cm²
We apply the equation
Te = k*(V/A)ⁿ
⇒ Te = (6.4 s/cm²)*(24.5436 cm³/4.9087 cm²)²
⇒ Te = 160 s
Consider incompressible flow in a circular channel. Derive general expressions for Reynolds number in terms of (a) volume flow rate Q and tube diameter D and (b) mass flow rate mp and tube diameter. The Reynolds number is 1800 in a section where the tube diameter is 6 mm. (c) Find the Reynolds number for the same flow rate in a section where the tube diameter is 6 mm.
Answers
Answer:
a) [tex]Re = \frac{4\cdot \rho \cdot Q}{\pi\cdot \mu\cdot D}[/tex], b) [tex]Re = \frac{4\cdot \dot m}{\pi\cdot \mu\cdot D}[/tex], c) 1600
Explanation:
a) The Reynolds Number is modelled after the following formula:
[tex]Re = \frac{\rho \cdot v \cdot D}{\mu}[/tex]
Where:
[tex]\rho[/tex] - Fluid density.
[tex]\mu[/tex] - Dynamics viscosity.
[tex]D[/tex] - Diameter of the tube.
[tex]v[/tex] - Fluid speed.
The formula can be expanded as follows:
[tex]Re = \frac{\rho \cdot \frac{4Q}{\pi\cdot D^{2}}\cdot D }{\mu}[/tex]
[tex]Re = \frac{4\cdot \rho \cdot Q}{\pi\cdot \mu\cdot D}[/tex]
b) The Reynolds Number has this alternative form:
[tex]Re = \frac{4\cdot \dot m}{\pi\cdot \mu\cdot D}[/tex]
c) Since the diameter is the same than original tube, the Reynolds number is 1600.
A two-dimensional reducing bend has a linear velocity profile at section (1) . The flow is uniform at sections (2) and (3). The fluid is incompressible and the flow is steady. Find the maximum velocity, V1,max, at section (1).
Answers
To find the maximum velocity at section (1) in a two-dimensional reducing bend with a linear velocity profile, apply the principle of conservation of mass and the equation Q = Av. The maximum velocity, V1,max, occurs at section (1) where the cross-sectional area is the smallest.
Explanation:To find the maximum velocity, V1,max, at section (1) in a two-dimensional reducing bend with a linear velocity profile at section (1), we can apply the principle of conservation of mass. As the cross-sectional area decreases, the velocity increases to maintain constant flow rate. At section (1), the velocity is maximum due to the smallest area.
Using the equation Q = Av, where Q is the flow rate, A is the cross-sectional area, and v is the velocity, we can determine the maximum velocity at section (1). The maximum velocity, V1,max, occurs at section (1) where the cross-sectional area is the smallest, resulting in the highest velocity to maintain flow rate continuity.
Construction of a reservoir behind a dam Group of answer choices
a. stabilizes the sides of reservoir walls; the water buoys them up.
b. destabilizes the slopes because of the weight of the dam.
c. can destablize the slopes by increasing pore fluid pressure.
d. has no effect on slope stability.
Answers
Answer:
c. can destablize the slopes by increasing pore fluid pressure.
Explanation: A reservoir is a term used in Agriculture or geography to describe a location where water is either collected artificially or naturally for later use in farming or to act as dam for the supply of water in large communities. Most countries of the world make use of reservoirs to store water for future use.
1. The following is a lumped model for an antenna. The input is vin and we are interested in the current through the inductor, iout. 0.5 F 0.5 H 0.5 Ω + − vin iout (a) Find the transfer function G(s) = Iout(s) Vin(s) (b) Use the linear approximation rules to sketch the Bode Plot for G(s). (c) According to your sketch, what is the steady state output if the input is vin(t) = cos(10t)?
Answers
Answer:
(a) [tex]G(s) = \frac{i_{out(s)}}{v_{in}(s)} = \frac{2S}{S^2+4S+4}[/tex]
(b) see plot in the attached explanation.
(c) [tex]i_{out}(t) = 0.2 Cos(10t-63)[/tex]
Explanation:
See attached solution a to c
A voltage regulator is to provide a constant DC voltage Vl=10V to a load Rl from a nominal Vcc=15V supply voltage. The load can vary from 20Ω to 1KΩ. The supply voltage Vcc can vary from 13V to 16V. The op-amp can provide a maximum output current of 20mA. a)Find the βnecessary for the transistor to provide the needed current. b)Find the maximum power the transistor must dissipate.
Answers
Answer:
Beta values can be from the equation=change in Vcc/nominal Vcc
Beta=16-3/15=3/15=1/5=0.20
Maximum power=I^2*R=40 W
a steam coil is immersed in a stirred heating tank. Saturated steam at 7.50 bar condenses within the coil , and the condensate emerges at at its saturation temperature. A solvent with a heat capacity of 2.30 kJ is fed to the tank at a steady rate of 12.0 kg/min and a temperature of 25°C, and the heated solvent is discharged at the same flow rate. The tank is initially filled with 760 kg of solvent at 25°C, at which point the flows of both steam and solvent are commenced. The rate at which heat is transferred from the steam coil to the solvent is given by the expression where UA (the product of a heat transfer coefficient and the area through which the heat is transferred) equals 11.5 kJ/min·°C. The tank is well stirred, so that the temperature of the contents is spatially uniform and equals the outlet temperature.
Write a differential energy balance on the tank contents.
Answers
Answer:
d/dt[mCp(Ts-Ti)] = FCp(Ts-Ti) - FoCp(Ts-Ti) + uA(Ts-Ti)
Explanation:
Differential balance equation on the tank is given as;
Accumulation = energy of inlet steam - energy of outlet steam+ heat transfer from the steamwhere;Accumulation = d/dt[mcp(Ts-Ti)]
Energy of inlet steam = FCp(Ts-Ti)
Energy of outlet steam = FoCp(Ts-Ti)
Heat transfer from the steam = uA(Ts-Ti)
Substituting into the formula, we have;
Accumulation = energy of inlet steam - energy of outlet steam+ heat transfer from the steamd/dt[mCp(Ts-Ti)] = FCp(Ts-Ti) - FoCp(Ts-Ti) + uA(Ts-Ti)The differential energy balance is [tex]\(\frac{dT}{dt} = \frac{11.5 T_s + 690 - 39.1 T}{1748}\).[/tex]
To write a differential energy balance on the tank contents, we need to consider the energy entering and leaving the system. The system in question is the well-stirred heating tank. Here are the steps to formulate the energy balance:
1. Define the system and parameters:
- The solvent enters the tank at a flow rate of 12.0 kg/min and at a temperature of 25°C.
- The solvent has a heat capacity [tex]\( C_p = 2.30 \text{ kJ/kg°C} \).[/tex]
- The tank is initially filled with 760 kg of solvent at 25°C.
- Heat transfer rate from the steam coil to the solvent is given by
[tex]\( UA(T_s - T) \)[/tex] where [tex]\( UA = 11.5 \text{ kJ/min·°C} \), \( T_s \)[/tex] is the steam temperature, and ( T ) is the solvent temperature.
- The tank is well-stirred, ensuring uniform temperature throughout, and the outlet temperature equals the tank temperature.
2. Energy balance:
The energy balance for a well-stirred tank in differential form is given by:
[tex]\[ \frac{d(U)}{dt} = \dot{Q}_{\text{in}} + \dot{m} C_p T_{\text{in}} - \dot{m} C_p T_{\text{out}} \][/tex]
Where:
- ( U ) is the internal energy of the tank contents.
[tex]- \( \dot{Q}_{\text{in}} \)[/tex] is the heat transfer rate from the steam coil.
[tex]- \( \dot{m} \)[/tex] is the mass flow rate of the solvent.
[tex]- \( T_{\text{in}} \)[/tex] is the inlet temperature of the solvent.
[tex]- \( T_{\text{out}} \)[/tex] of the solvent (equal to tank temperature ( T ).
Since [tex]\( \dot{m}_{\text{in}} = \dot{m}_{\text{out}} = \dot{m} \) and \( T_{\text{out}} = T \):[/tex]
[tex]\[ \frac{d(U)}{dt} = UA(T_s - T) + \dot{m} C_p (T_{\text{in}} - T) \][/tex]
3. Internal energy change:
The internal energy change of the tank contents can be expressed as:
[tex]\[ \frac{d(U)}{dt} = m C_p \frac{dT}{dt} \][/tex]
Where ( m ) is the mass of the solvent in the tank (760 kg) and ( T ) is the solvent temperature in the tank.
4. Combine the equations:
Substituting [tex]\( \frac{d(U)}{dt} = m C_p \frac{dT}{dt} \)[/tex] into the energy balance:
[tex]\[ m C_p \frac{dT}{dt} = UA(T_s - T) + \dot{m} C_p (T_{\text{in}} - T) \][/tex]
5. Simplify the equation:
Substitute the given values:
[tex]- \( m = 760 \text{ kg} \)\\ - \( C_p = 2.30 \text{ kJ/kg°C} \)\\ - \( \dot{m} = 12.0 \text{ kg/min} \) - \( UA = 11.5 \text{ kJ/min·°C} \)\\ - \( T_{\text{in}} = 25 \text{ °C} \)[/tex]
[tex]\[ 760 \cdot 2.30 \frac{dT}{dt} = 11.5 (T_s - T) + 12.0 \cdot 2.30 (25 - T) \][/tex]
Simplify to:
[tex]\frac{dT}{dt} = 11.5 (T_s - T) + 27.6 (25 - T) \]\[ 1748[/tex]
Further simplify:
[tex]\[ 1748 \frac{dT}{dt} = 11.5 T_s - 11.5 T + 690 - 27.6 T \][/tex]
Combine like terms:
[tex]\[ 1748 \frac{dT}{dt} = 11.5 T_s + 690 - 39.1 T \][/tex]
Finally:
[tex]\[ \frac{dT}{dt} = \frac{11.5 T_s + 690 - 39.1 T}{1748} \][/tex]
This is the differential energy balance equation for the tank contents.
A prototype of a part is to be fabricated using stereolithography. The part is shaped like a right triangle whose base = 36 mm, height 48mm, and thickness = 30 mm. In the stereolithography process, the layer thickness = 0.15 mm. Diameter of the laser beam spot = 0.40 mm, and the beam is moved across the surface of the photopolymer at a velocity of 2200 mm/s. Compute the minimum possible time (use units of hours, 3 significant figs) required to build the part, if 25 s are lost each layer to lower the height of the platform that holds the part. Neglect the time for setup and post-processing.
Answers
Answer:
1.443hrs
Explanation:
Please kindly check attachment for the detailed and step by step solution to the problem.
Air enters a compressor steadily at the ambient conditions of 100 kPa and 22°C and leaves at 800 kPa. Heat is lost from the compressor in the amount of 120 kJ/kg, and the air experiences an entropy decrease of 0.40 kJ/kg·K. Using constant specific heats, determine
(a) the exit temperature of the air,
(b) the work input to the compressor, and
(c) the entropy generation during this process.
Answers
Answer:
a) 358.8K
b) 181.1 kJ/kg.K
c) 0.0068 kJ/kg.K
Explanation:
Given:
P1 = 100kPa
P2= 800kPa
T1 = 22°C = 22+273 = 295K
q_out = 120 kJ/kg
∆S_air = 0.40 kJ/kg.k
T2 =??
a) Using the formula for change in entropy of air, we have:
∆S_air = [tex] c_p In \frac{T_2}{T_1} - Rln \frac{P_2}{P_1}[/tex]
Let's take gas constant, Cp= 1.005 kJ/kg.K and R = 0.287 kJ/kg.K
Solving, we have:
[/tex] -0.40= (1.005)ln\frac{T_2}{295} ln\frac{800}{100}[/tex]
[tex] -0.40= 1.005(ln T_2 - 5.68697)- 0.5968[/tex]
Solving for T2 we have:
[tex] T_2 = 5.8828[/tex]
Taking the exponential on the equation (both sides), we have:
[/tex] T_2 = e^5^.^8^8^2^8 = 358.8K[/tex]
b) Work input to compressor:
[tex] w_in = c_p(T_2 - T_1)+q_out[/tex]
[tex] w_in = 1.005(358.8 - 295)+120[/tex]
= 184.1 kJ/kg
c) Entropy genered during this process, we use the expression;
Egen = ∆Eair + ∆Es
Where; Egen = generated entropy
∆Eair = Entropy change of air in compressor
∆Es = Entropy change in surrounding.
We need to first find ∆Es, since it is unknown.
Therefore ∆Es = [tex] \frac{q_out}{T_1}[/tex]
[tex] \frac{120kJ/kg.k}{295K}[/tex]
∆Es = 0.4068kJ/kg.k
Hence, entropy generated, Egen will be calculated as:
= -0.40 kJ/kg.K + 0.40608kJ/kg.K
= 0.0068kJ/kg.k
Consider the expression for the change in entropy of the air.
[tex]\to \Delta S_{air}=c_p \ \In \frac{T_2}{T_1} - R \In \frac{P_2}{P_1} \\\\[/tex]
Here, change in entropy of air in a compressor is[tex]\Delta S_{air}[/tex], specific heat at constant pressure is [tex]c_p[/tex], the inlet temperature is [tex]T_1[/tex], outlet temperature is [tex]T_2[/tex], the gas constant is R, inlet pressure is [tex]P_1[/tex], and outlet pressure is[tex]P_2[/tex].
From the ideal gas specific heats of various common gases table, select the specific heat at constant pressure[tex]c_p[/tex] and gas constant (R) at air and temperature:
[tex]\to 22\ C \ \ or \ \ 295\ K\ \ as 1.005 \ \frac{kJ}{kg \cdot K} \ \ and \ \ 0.287\ \frac{kJ}{kg \cdot K}[/tex]
Substituting
Take exponential on both sides of the equation.
[tex]\to T_2 = exp(5.8828) = 358.8\ K \\\\[/tex]
Hence, the exit temperature of the air is [tex]358.8\ K[/tex]. Apply the energy balance to calculate the work input.
[tex]\to W_{in}=c_p(T_2-T_1 )+q_{out}[/tex]
Here, work input is [tex]w_{in}[/tex] initial temperature is [tex]T_1[/tex], exit temperature is [tex]T_2[/tex], and heat transfer outlet is [tex]q_{out}[/tex]
Substituting
Hence, the work input to the compressor is
Express the entropy generated in the process.
[tex]\to S_{gen} =\Delta S_{air}+\Delta S_{swr}[/tex]
Here, entropy generated is [tex]S_{gen}[/tex], change in entropy of air in a compressor is [tex]\Delta S_{air}[/tex], and change in entropy in the surrounding is [tex]\Delta S_{swr}[/tex].
Finding the changes into the surrounded entropy.
[tex]\to \Delta S_{swr} = \frac{q_{out}}{T_{swr}}[/tex]
Here, the heat transfer outlet is [tex]q_{out}[/tex] and the surrounded temperature is [tex]T_{swr}[/tex].
Substituting
[tex]120\ \frac{kJ}kg } \ for\ q_{out} \ and\ 22\ C \ for\ T_{swr}[/tex]
[tex]\Delta S_{swr} = \frac{ 120\frac{kJ}{kg}}{(22+273)\ K} =0.4068 \frac{kJ}{kg\cdot K}[/tex]
Finding the entropy generated process.
[tex]S_{gen} = \Delta S_{air} +\Delta S_{swr}\\[/tex]
Substituting
[tex]-0.40 \frac{kJ}kg\cdot K} \ for \ \Delta S_{air},\ and\ 0.4068 \frac{kJ}{kg\cdot K}\ for\ \Delta S_{swr}\\\\[/tex]
[tex]S_{gen}=-0.40 \frac{kJ}{kg\cdot K} +0.4068 \frac{kJ}{kg\cdot K} = 0.0068 \frac{kJ}{kg\cdot K}[/tex]
Therefore, the entropy generated in the process is [tex]0.0068\ \frac{kJ}{kgK}[/tex].
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A circular specimen of MgO is loaded in three-point bending. Calculate the minimum possible radius of the specimen without fracture, given that: the applied load is 5560 N the flexural strength is 105 MPa the separation between the supports is 45 mm Input your answer as X.XX mm, but without the unit of mm.
Answers
Answer:
radius = 9.1 × [tex]10^{-3}[/tex] m
Explanation:
given data
applied load = 5560 N
flexural strength = 105 MPa
separation between the support = 45 mm
solution
we apply here minimum radius formula that is
radius = [tex]\sqrt[3]{\frac{FL}{\sigma \pi}}[/tex] .................1
here F is applied load and is length
put here value and we get
radius = [tex]\sqrt[3]{\frac{5560\times 45\times 10^{-3}}{105 \times 10^6 \pi}}[/tex]
solve it we get
radius = 9.1 × [tex]10^{-3}[/tex] m
For a steel alloy it has been determined that a carburizing heat treatment of 7 hour duration will raise the carbon concentration to 0.38 wt% at a point 3.8 mm from the surface. Estimate the time (in hours) necessary to achieve the same concentration at a 6.2 mm position for an identical steel and at the same carburizing temperature.
Answers
Answer:
18.6h
Explanation:
To solve this Duck's second law in form of Diffusion will be used.
Also note that since the temperature is constant D (change) will also be constant.
Please go through the attached files for further explanation and how the answer Is gotten.
A and B connect the gear box to the wheel assemblies of a tractor, and shaft C connects it to the engine. Shafts A and Blie in the vertical yz plane, while shaft C is directed along the x axis. Replace the couples applied to the shafts with a single equivalent couple, specifying its magnitude and the direction of its axis.
Answers
The couplings are not all on the same axis or plane, but if the A and B connector were to be described, it would travel with a magnitude of roughly 15 by the yz axis diagonal to the x axis. The axis would be oriented so that it was pointing upward into the second quadrant.
What is magnitude?In terms of physics, magnitude is just "distance or quantity." It displays an object's size, direction, or motion in absolute or relative terms. It is employed to indicate the size or scope of something.
In physics, the term "magnitude" often refers to a size or amount. Magnitude is defined as "how much of a quantity." The magnitude can be used, for instance, to compare the speeds of a car and a bicycle.
It can also be used to indicate how far something has come or how much something weighs relative to its size.
Thus, The couplings are not all on the same axis or plane.
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