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3 years ago

In alternating current, how often does the current alternate between negatively and postively?

2 answers:

4 0

In an alternating current (AC) circuit the two poles alternate between negative and positive and the direction of the current (electron flow) reverses periodically.

strojnjashka [21]3 years ago

4 0

1/60th of a second each way back and forth

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Define the isentropic efficiency for each of the following 3. a. i. Adiabatic turbine ii. Adiabatic compressor iii. Adiabatic no

Pavlova-9 [17]

Answer:

a) $\eta_{st}=\dfrac{\Delta h_{actual}}{\Delta _{ideal}}$

b) $\eta_{sc}=\dfrac{\Delta h_{ideal}}{\Delta _{actual}}$

c) $\eta_{sn}=\dfrac{\Delta h_{actual}}{\Delta _{ideal}}$

Explanation:

Adiabatic turbine

Adiabatic turbine means turbine can not reject or take heat from surrounding.

Isentropic efficiency of turbine can be define as the ratio of actual work out put to the Ideal or isentropic work out put.Ideal means when turbine will give maximum work and there is no any friction losses we can say when process is isentropic.

Isentropic efficiency of turbine=(Actual work output)/(Ideal work output)

$\eta_{st}=\dfrac{\Delta h_{actual}}{\Delta _{ideal}}$

Adiabatic compressor

Isentropic efficiency of compressor can be define as the ratio of ideal or isentropic work in put to the actual work in put.

Isentropic efficiency of turbine=(Ideal work input)/(actual work input)

$\eta_{sc}=\dfrac{\Delta h_{ideal}}{\Delta _{actual}}$

c)Adiabatic nozzle

We know that nozzle is device which used to accelerate the fluid.

Basically it covert pressure energy to kinetic energy.

Isentropic efficiency of nozzle can be define as the ratio of actual enthalpy drop put to the Ideal or isentropic enthalpy drop.

$\eta_{sn}=\dfrac{\Delta h_{actual}}{\Delta _{ideal}}$

3 0

4 years ago

A large plate is fabricated from a steel alloy that has a plane strain fracture toughness of 50.0 MPa-m1/2 . If, during service

Studentka2010 [4]

Answer:

The answer is " $0.0199044586 \ m\\\\$ ".

Explanation:

The crucial stress essential for activating the spreading of the crack is $\sigma$ , the hardness of the strain break is K, as well as the area long of a break is a, for dimensionless Y. Its equation of the length of its surface of the fracture is 50.1 MPa $\sqrt{m}$ on K, 200MPa on $\sigma$ , and 1 on Y.

$a = \frac{1}{\pi} (\frac{K}{Y \ \sigma} )^2 \\\\$

$= \frac{1}{\pi} ( \frac{50.0}{1 \times 200} )^2 \\\\= \frac{1}{3.14} ( \frac{1}{4})^2 \\\\= \frac{1}{3.14} ( \frac{1}{16}) \\\\=\frac{1}{50.24}\\\\=0.0199044586 \ m\\\\$

4 0

3 years ago

Need help, I will give cake :))<br><br> + branliest

Talja [164]

Answer:

Explanation:

it goes good with it.

3 0

3 years ago

Read 2 more answers

______number can be used to describe the relative growth of the hydraulic boundary layer and the thermal boundary layer. a) Reyn

weqwewe [10]

Answer: d) Prandtl number

Explanation: Prandtl number is basically defined as the ratio between the fluid's viscosity to the thermal conductivity.It doesn't have any sort of dimension. The fluids which are discovered with the small Prandtl numbers are considered as good fluids as they have a smooth rate of flow and as the number increases the fluid are not considered as reliable. Thus,option (d) is the correct option.

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4 years ago

Strong performance in your engineering discipline ordinarily is one necessary condition for becoming a successful engineering ma

zhenek [66]

Answer:

1. Manpower Management

2. Productive Meetings

3.Establish administrative policies, procedures, and standards.

4. High command over assets management.

5. Specific field related knowledge of procurement.

6. Compliance and EHS knowledge.

Explanation:

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3 years ago