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3 years ago

List one advantage and one disadvantage of the use of the commutator?

Engineering

1 answer:

Mariulka [41]3 years ago

3 0

Answer and Explanation:

Commutator are used in DC machine commutator is mainly used for the reversing the direction of the current .It is connected to the armature of the DC generator or motor

ADVANTAGE OF COMMUTATOR The main advantage of the commutator in DC motor is to keep keep the direction of the toque always in the same direction by changing the current direction

DISADVANTAGE OF COMMUTATOR : The main disadvantage is due to the friction between the commutator and brushes there is a friction loss.

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Listed below are snippets from a prgram to perform input validation for

leva [86]

Answer:

#include <iostream>

#include <string>

#include "user.h"

#include "password.h"

using namespace Authenticate;

using namespace std;

int main()

{

inputUserName();

inputPassword();

cout << "Your username is " << getUserName() <<

" and your password is: " <<

getPassword() << endl;

return 0;

}

user.h:

#ifndef USER_H

#define USER_H

#include <string>

using namespace std;

namespace Authenticate

{

namespace

{

bool isvalid();

}

void inputUserName();

string getUserName();

}

#endif

user.cpp:

#include <iostream>

#include "user.h"

namespace Authenticate

{

string username="";

namespace

{

bool isvalid()

{

if(username.length() == 8)

return true;

else

return false;

}

void inputUserName(){

{

cout << "Enter your username (8 letters only)" << endl;

cin >> username;

}

while(!isvalid());

}

string getUserName()

{

return username;

}

password.h:

#ifndef PASSWORD_h

#define PASSWORD_h

#include <string>

using namespace std;

namespace Authenticate

{

namespace

{

bool isValid();

}

void inputPassword();

string getPassword();

}

#endif

password.cpp:

#include <iostream>

#include <string>

using namespace std;

namespace Authenticate

{

string password="";

namespace

{

bool isValid()

{

if(password.length() >= 8)

{

for(int i=0; i<password.length(); i++)

if(password[i] >= '0' && password[i] <= '9')

return true;

return false;

}

else

return false;

}

void inputPassword(){

{

cout << "Enter your password (at least 8 characters " <<

"and at leat one non-letter)" << endl;

cin >> password;

}

while(!isValid());

}

string getPassword()

{

return password;

}

3 0

3 years ago

A group of students launches a model rocket in the vertical direction. Based on tracking data, they determine that the altitude

Fofino [41]

Answer:

$u = 260.22m/s$

$S_{max} = 1141.07ft$

Explanation:

Given

$S_0 = 89.6ft$ --- Initial altitude

$S_{16.5} = 0ft$ -- Altitude after 16.5 seconds

$a = -g = -32.2ft/s^2$ --- Acceleration (It is negative because it is an upward movement i.e. against gravity)

Solving (a): Final Speed of the rocket

To do this, we make use of:

$S = ut + \frac{1}{2}at^2$

The final altitude after 16.5 seconds is represented as:

$S_{16.5} = S_0 + ut + \frac{1}{2}at^2$

Substitute the following values:

$S_0 = 89.6ft$ $S_{16.5} = 0ft$ $a = -g = -32.2ft/s^2$ and $t = 16.5$

So, we have:

$0 = 89.6 + u * 16.5 - \frac{1}{2} * 32.2 * 16.5^2$

$0 = 89.6 + u * 16.5 - \frac{1}{2} * 8766.45$

$0 = 89.6 + 16.5u- 4383.225$

Collect Like Terms

$16.5u = -89.6 +4383.225$

$16.5u = 4293.625$

Make u the subject

$u = \frac{4293.625}{16.5}$

$u = 260.21969697$

$u = 260.22m/s$

Solving (b): The maximum height attained

First, we calculate the time taken to attain the maximum height.

Using:

$v=u + at$

At the maximum height:

$v =0$ --- The final velocity

$u = 260.22m/s$

$a = -g = -32.2ft/s^2$

So, we have:

$0 = 260.22 - 32.2t$

Collect Like Terms

$32.2t = 260.22$

Make t the subject

$t = \frac{260.22}{ 32.2}$

$t = 8.08s$

The maximum height is then calculated as:

$S_{max} = S_0 + ut + \frac{1}{2}at^2$

This gives:

$S_{max} = 89.6 + 260.22 * 8.08 - \frac{1}{2} * 32.2 * 8.08^2$

$S_{max} = 89.6 + 260.22 * 8.08 - \frac{1}{2} * 2102.22$

$S_{max} = 89.6 + 260.22 * 8.08 - 1051.11$

$S_{max} = 1141.0676$

$S_{max} = 1141.07ft$

Hence, the maximum height is 1141.07ft

8 0

3 years ago

The acceleration of a particle as it moves along a straight line is given

BARSIC [14]

Answer:

V_t=6 = 32 m/s

Explanation:

The origin is at point 0 with the positive motion to the right

The instantaneous acceleration is change of velocity measured at infinitesimal interval of time, so the expression for instantaneous acceleration is:

a=dv/dt

From here we can express dv as:

dv = a dt

Replace a by 2t — 1

dv = (2t — 1) dt

Integrate both sides of equation

$\int\limits^v_a {2t-1} \, dv$

v=t

a=t_0

putting these value in integral

We know that v_0 = 2 at t_0 = 0, so we'll replace t_0 and v_0 by their values

v — 2 = (t^2 — t) — (0^2 — 0)

From here we can write the expression for v as:

v_t=6=6^2-6+2 (1)

So the velocity at t = 6 s is:

v_t=6 = 32 m/s

V_t=6 = 32 m/s

In order to determine the total distance travelled, we must check how maw times the particle has changed its direction, i.e. how many times its speed was equal to zero

To do that, we'll just replace v by 0 in expression (1)

0 = t^2 — t + 2

The roots of the quadratic equation are:

t_1/2=1± √(1^2-4*2*1)/2

Since 1^2-4*2*1 < 0, the quadratic equation have no real roots, so we can say that the velocity is always positive, i.e. to the right

Now that we have all the details, we can correctly draw the path of the particle

We can see from the sketch that the total distance traveled is:

s^T=Δs_0-1

s^T=| s_1 - s_0 |

Replace s_0 by its value

s^T=| s_1 - 1 | (2)

In order to determine the position of particle at t = 6 s, we'll need to determine the expression for s as function of time

Since we have already wrote expression for v as function of time (step 2), we'll use expression to get the expression for s

v= ds/dt

Multiply both sides of equation by dt

v dt = ds

Replace v by expression (1)

(t^2 — t + 2) dt = ds

Integrate both sides of equation

$\int\limits^t_b {x} \, dx$

t=s

b=(s=0)

x=(t^2 — t + 2)

dx=ds

putting these value in integral

(t^3/3-t^2/2+t)-(t_0^3/3-t_0^2/2+t_0)= s-s_0

Since s = 1 m at t = 0, and we want to determine the position s at t = 6, we'll replace so by 1, t_0 by 0 and t by 6

(6^3/3-6^2/2+6)-(0^3/3-0^2/2+0)=s_t=6-1

4 0

3 years ago

What steps should Ben follow to prepare for a hurricane?

RSB [31]

A. All the answers are correct (All of the above).

3 0

4 years ago

Read 2 more answers

The worst case signal-to-noise ratio at the output of an FM detector occurs when: ________

AlexFokin [52]

Answer:

a. the desired signal is 90 degrees out of phase with the intelligence signal.

Explanation:

The signal to noise ratio of FM detector is defined as function of modulation index for SSB FM signal plus narrow band Gaussian noise at input. The ratio is usually higher than 1:1 which indicates more signals than noise.

6 0

3 years ago