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3 years ago

List two useful properties of current electricity and explain why.

1 answer:

6 0

One example of current electricity are transmission lines. These bring electricity from power stations to individual houses.

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how does the number of chromosomes in a persons sex compare with the number of chromosome in the body cell

koban [17]

no it doesn't why because I think that it is not the same but different.

4 0

3 years ago

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

Which form of emission is commonly not written in nuclear equations because they do not affect charges, atomic numbers, or mass

salantis [7]

Answer:

Gamma radiation .

Explanation:

Three types of emission result at the time of nuclear emission .

alpha emission

Beta emission

Gamma radiation emission

Gamma radiation results in the emission of gamma ray . This is a very high frequency radiation . It is not a particle having charge and mass like alpha and beta emission . So it has no effect on the mass and charge of the product that is formed after gamma radiation . The only effect it has on the product is that it reduces the kinetic energy of the emitting particles or it reduces the internal energy of the product . It causes negligible change in the mass of the product and no change in the charge of the product.

That is why , generally this product is not written in the nuclear reaction .

4 0

3 years ago

Compare convection currents in the ocean with convection currents in the atmosphere. Use complete sentences and give at least tw

KIM [24]

In this way, heat inside Earth moves toward the cooler crust. This movement of rock is a COnvection Current. Convection Currents in the mantle cause the movement of tectonic plates. Figure 4 Convection currents in the atmosphere form when cold airsinks and forces warm air away from Earth's surface.

4 0

3 years ago

Read 2 more answers

The specific heat capacity of solid copper metal is 0.385 J/gK. How many joules of heat are needed to raise the temperature of a

SSSSS [86.1K]

Answer: 26.6 J

Explanation:

The heat needed to raise the temperature of a solid body, using only a conductive process, has been empirically showed to be equal to the following expression:

Q= c . m. (t2 – t1)

where c= specific heat capacity (in J/gK), m= mass of the solid (in g) ,

and (t2 - t1)= difference between final and initial temperatures.

Replacing by the values, we get:

Q= 0.385 J/gK . 1,550 g. (77.5ºC – 33.0ºC)= 26.6 J

3 0

3 years ago