Recent content by qpzm77gg

How to change the upper step to lower step on the figure? Why does N2(0) change to N2(t) the exp(-t/21) will be missed? Thanks.

Q2. switch level, Gate level, Behavioral level ? Is't correct? Q3. How to illustrate?? I still not know Q4. The function of CPU in PLC are communication with the memory, perform logic and arithmetic operations, updating the inputs and outputs. Is't correct?? Besides, how to illustrate that...

Problems of control and automation, help please! 2. What are the 4 classes of programming languages of PLC? 3. How to illustrate the meaning of control system in control and automation system? 4. How to illustrate the major role of CPU in a PLC and what is the major role of CPU? 5...

What kind of engineering involves the most physics? It focus on modern physics is the best.

But I have some problems about it. v=rθ /t θ /t = angular velocity Why speed = radius x angular velocity? I think velocity = radius x angular velocity is suitable for it.

What is the difference among moment, torque and couple? Moment = Fd Torque = Fd Couple mean two forces have same magnitude but opposite direction. What is the relationship among them?

Thanks. I understand now. The equation of (1) is not velocity=displacement/time, but speed=distance/time, right?

1. v=s/t where s represents the displacement 2. s=rθ where s represents the arc length v=rθ /t Why can substitute here? I guess that is not same things. An arc length is not a straight line but displacement is which is shortest distance between initial and final point.

QT = QL-Qc Because all I are same in the in series circuit. XT=XL - Xc QT/I2=188.5-Xc Xc = 1186.19Ω another method, |Z|=1662.82 |Z|2 = R2+Xc22 1662.822 = 1002+Xc22 Xc2=1659.8Ω QT=I2(1659.8) QT=0.0432VAR(cap) Qc=QL-QT Qc=0.0049+0.0432=0.0481VAR(cap) Xc=0.0481/0.00512=1849.3Ω...

The complete question is uploaded in the file. Thanks a lot.

Yes, They are same as before, and then step and step add the capacitor in the circuit and change the power factor from 1 to 0.8. Thanks

R = 100Ω, L=0.5H, supply voltage vs(t) = 12sin(377t) in Figure 1a XL = wL =377(0.5) = 188.5Ω vrms = 8.485∠0 Z=213.38∠62.05 Ω I = 8.485∠0/ 213.38∠62.05 = 0.0398∠-62.05 A VR = 3.98∠-62.05 V VL = 7.502∠27.95 V PT = 0.0398[SUP]2[SUP](100) = 0.158W QT = QL = 0.299 VAR ST = 0.338∠62.05 VA Fp =...

supplementary one of my problems. Is't necessary the moment method to solve this questions? Thanks

The first picture is the question picture. The second picture is my calculation for this questions. I can't find the correct answer, everybody know why? Thanks

I can find the total resistance and then I found out the total current is 0.1344A by V=IR. But I can't find the current in the no resistor wire I which the question need to find it.