5b. The object George is examining has a mass of 15 grams. What is the density of the object?

A 4-pole, 3-phase induction motor operates from a supply whose frequency is 60 Hz. calculate: 1- the speed at which the magnetic

DiKsa [7]

Answer:

The answer is below

Explanation:

1) The synchronous speed of an induction motor is the speed of the magnetic field of the stator. It is given by:

$n_s=\frac{120f_s}{p}\\ Where\ p\ is \ the \ number\ of\ machine\ pole, f_s\ is\ the\ supply \ frequency\\and\ n_s\ is \ the \ synchronous\ speed(speed \ of\ stator\ magnetic \ field)\\Given: f_s=60\ Hz, p=4. Therefore\\\\n_s=\frac{120*60}{4}=1800\ rpm$

2) The speed of the rotor is the motor speed. The slip is given by:

$Slip=\frac{n_s-n_m}{n_s}. \\ n_m\ is\ the \ motor\ speed(rotor\ speed)\\Slip = 0.05, n_s= 1800\ rpm\\ \\0.05=\frac{1800-n_m}{1800}\\\\ 1800-n_m=90\\\\n_m=1800-90=1710\ rpm$

3) The frequency of the rotor is given as:

$f_r=slip*f_s\\f_r=0.04*60=2.4\ Hz$

4) At standstill, the speed of the motor is 0, therefore the slip is 1.

The frequency of the rotor is given as:

$f_r=slip*f_s\\f_r=1*60=60\ Hz$

6 0

3 years ago

Handsaw teeth are very sharp: to avoid being cut by the teeth, keep hands and fingers well away from the

siniylev [52]

Handsaw teeth are very sharp: to avoid being cut by the teeth, keep hands and fingers well away from the
path of the blade

6 0

2 years ago

Read 2 more answers

A person is planning a bungee jump from a 40 meter high bridge. Under the bridge is a river with crocodiles, so the person does

Nonamiya [84]

Answer:

a. l = 19.7m, b. 18.55m, c. Impact Force = 3889.84 N

Explanation:

The total energy of the system when the person is at top of the bridge is

Potential energy = mgh, Kinetic energy = 0

The total energy of the system when the person reaches just above the surface

Potential energy = 0, Kinetic energy = 0, Spring energy = ½ K X2, where k is the spring constant and X is the deflection

Applying conservation of energy

mgh = 0 + 0 + ½ K X²

80 x 9.81 x 40 = ½ (3600/l) X²

31392 = ½ (3600/l) X²

We can also conclude that

l+ X + 1.75 = 40

l + X = 38.25

a. Substitute the value of x from above into the energy conversion expression

31392 = ½ (3600/l)(38.25 - l)²

31392 x 2/3600 = (38.25 + l² – 2l(38.25))/l

17.44l = l2 – 76.5l + 38.25²

l² – 76.5l – 17.44l +1463.0625 = 0

Solving for l we get

L = 19.7

Hence, length of the rope is 19.7m

b. The deflection is calculated by using the relation between l and X

L + X = 38.25

X = 38.25 – 19.7 = 18.55m

c. The impact force is calculated using the impact force formula which relates the impact force with the deflection

F = KX

F = (3600/l) . X

F = (3600/19.7) . (18.55) = 3889.84 N

Thus, the impact force is 3889.84 N

3 0

3 years ago

What is the locating position of the land field?

Ivahew [28]

Any point on earth can be located by specifying its latitude and longitude, including Washington, DC, which is pictured here. Lines of latitude and longitude form an imaginary global grid system, shown in Fig. 1.17. Any point on the globe can be located exactly by specifying its latitude and longitude.

4 0

2 years ago

Reference Parameters (returning multiple values): Write a C++ function that converts standard time to military time. Inputs incl

valkas [14]

Answer:

Code is given as below:

Explanation:

#include <iostream>

using namespace std;

//function prototype declaration

void MilitaryTime(int, int, char, int &, int &);

int main()

{

//declare required variables

int SHour, SMin, MHour, MMin;

char AorP;

//promt and read the hours from the user

cout<<"Enter hours in standard time : ";

cin>>SHour;

//check the hours are valid are not

while(SHour<0 || SHour>12)

{

cout<<"Invalid hours for standard time. "

<<"Try again..."<<endl;

cout<<"Enter hours in standard time : ";

cin>>SHour;

}

//promt and read the minutes from the user

cout<<"Enter minutes in standard time : ";

cin>>SMin;

//check the minutes are valid are not

while(SMin<0 || SMin>59)

{

cout<<"Invalid minutes for standard time. "

<<"Try again..."<<endl;

cout<<"Enter minutes in standard time : ";

cin>>SMin;

}

//promt and read the am or pm from the user

cout<<"Enter standard time meridiem (a for AM p for PM): ";

cin>>AorP;

//check the meridiem is valid are not

while(!(AorP=='a' || AorP=='p' || AorP=='A' || AorP=='P'))

{

cout<<"Invalid meridiem for standard time. "

<<"Try again..."<<endl;

cout<<"Enter standard time meridiem (a for AM p for PM): ";

cin>>AorP;

}

//call function to calculate the military time

MilitaryTime(SHour, SMin, AorP, MHour, MMin);

//fill zeros and display standard time

cout.width(2);

cout.fill('0');

cout<<SHour<<":";

cout.width(2);

cout.fill('0');

cout<<SMin;

if(AorP=='a' || AorP=='A')

cout<<" am = ";

else

cout<<" pm = ";

//fill zeros and display military time

cout.width(2);

cout.fill('0');

cout<<MHour;

cout.width(2);

cout.fill('0');

cout<<MMin<<endl;

system("PAUSE");

return 0;

}

//function to calculate the military time with reference parameters

void MilitaryTime(int SHour, int SMin, char AorP, int &MHour, int &MMin)

{

//check the meredium is am or pm

//and calculate hours

if(AorP=='a' || AorP=='A')

{

if(SHour==12)

MHour = 0;

else

MHour = SHour;

}

else

MHour = SHour+12;

MMin = SMin;

5 0

3 years ago