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3 years ago

Which is the best procedure to make a permanent magnet?

Physics

2 answers:

notka56 [123]3 years ago

7 0

placing a magnetically hard material in a strong magnetic field

fgiga [73]3 years ago

3 0

<h3>Answer;</h3>

Placing a magnetically hard material in a strong magnetic field

<h3>Explanation;</h3>

Magnets are those materials that generate magnetic field. Materials may either be magnetic materials or non-magnetic materials. Non magnetic materials are those materials that can not be attracted by a magnet while magnetic materials are those that can be attracted by a magnet.
Magnetic materials may be classified as either soft magnetic materials or hard magnetic materials based on the ease of magnetization. Soft magnetic materials are those materials that are easily magnetized and easily demagnetized while hard magnetic materials are hard to magnetize and demagnetized.
Hard magnetic materials are used to make permanent magnets. This is done by placing them in a strong magnetic field.

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Steam flows steadily through an adiabatic turbine. The inlet conditions of the steam are 4 MPa, 500◦C, and 80 m/s, and the exit

Cerrena [4.2K]

Answer:

a) ΔEC=-23.4kW

b)W=12106.2kW

c) $A=0.01297m^2$

Explanation:

The kinetic energy is defined as:

$\frac{m*vel^2}{2}$ (vel is the velocity, to differentiate with v, specific volume).

The kinetic energy change will be: Δ ( $\frac{mvel^2}{2}$ )= $\frac{m*vel_2^2}{2}-\frac{m*vel_1^2}{2}$

Δ ( $\frac{mvel^2}{2}$ )= $\frac{m}{2}*(vel_2^2-vel_1^2)$

Where 1 and 2 subscripts mean initial and final state respectively.

Δ( $\frac{mvel^2}{2}$ )= $\frac{12\frac{kg}{s}}{2}*(50^2-80^2)\frac{m^2}{s^2}=-23400W=-23.4kW$

This amount is negative because the steam is losing that energy.

Consider the energy balance, with a neglective height difference: The energy that enters to the turbine (which is in the steam) is the same that goes out (which is in the steam and in the work done).

$H_1+\frac{m*vel_1^2}{2}=H_2+\frac{m*vel_2^2}{2}+W\\W=m*(h_1-h_2)+\frac{m}{2} *(vel_1^2-vel_2^2)$

We already know the last quantity: $\frac{m}{2} *(vel_1^2-vel_2^2)$ = $-$ Δ ( $\frac{mvel^2}{2}$ )=23400W

For the steam enthalpies, review the steam tables (I attach the ones that I used); according to that, $h_1=h(T=500C,P=4MPa)=3445.3\frac{kJ}{kg}$

The exit state is a liquid-vapor mixture, so its enthalpy is:

$h_2=h_f+xh_{fg}=289.23+0.92*2366.1=2483.4\frac{kJ}{kg}$

Finally, the work can be obtained:

$W=12\frac{kg}{s}*(3445.3-2438.4)\frac{kJ}{kg} +23.400kW)=12106.2kW$

C) For the area, consider the equation of mass flow:

$m=p*vel*A$ where $p$ is the density, and A the area. The density is the inverse of the specific volume, so $m=\frac{vel*A}{v}$

The specific volume of the inlet steam can be read also from the steam tables, and its value is: $0.08643\frac{m^3}{kg}$ , so:

$A=\frac{m*v}{vel}=\frac{12\frac{kg}{s}*0.08643\frac{m^3}{kg}}{80\frac{m}{s}}=0.01297m^2$

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7 0

3 years ago

When two or more different capacitors are connected in series across a potential source, which of the following statement must b

vova2212 [387]

Answer:

C. Each capacitor carries the same amount of charge.

Explanation:

When two or more different capacitors are connected in series across a potential source, each capacitor carries the same amount of charge.

In a series connected capacitor, sane amount of charge flows through the capacitors while different potential difference is passed across them.

The capacitors have the same charge as the charge flowing out directly from the potential source called emf since the emf is the driving force of charge in a circuit.

6 0

3 years ago

How much time does it take a person to walk 12km north at the velocity at a velocity of 6.5 km/hrs?

alukav5142 [94]

"6.5 km/hr" is not a velocity. It's just a speed, so
we don't know what direction he's walking.

If he happens to be walking north, then it takes him

(12 km) / (6.5 km/hr) = 1.846... hours (rounded) .

If he's walking in any other direction, it takes him longer than that.

If the angle between north and the direction he's walking is
90 degrees or more, then he can never cover any northward
distance, no matter how long he walks.

6 0

3 years ago

Read 2 more answers

A train travels 50 kilometers in 4 hours, and then 74 kilometers in 2 hours. What is its average speed?

olga55 [171]

Answer:

37.65

Explanation:

50/4 + 74/2

4 0

3 years ago

Read 2 more answers