# Search results

1. ### Shear stress question

Is Q not =y bar prime * A prime = 4r/3pi * (pi*r^2)/2 ?
2. ### Shear stress question

Homework Statement Homework Equations Mx=200Nm My=300Nm Mz=600Nm Normal stress caused by bending moment at A = Mc/I = (300*0.02)/((pi*0.02^4)/4)= 47.7MPa. This answer is correct. Shear stress by Torsional Moment=Tc/J Polar moment of inertia J=(pi/2)*c^4 So I...
3. ### Normal stress

I linked the problem and how it's solved, you must have missed it so here it is again
4. ### Normal stress

The problem Why is the normal stress 75/Area and not 125/Area. They are both acting on the same axis so how do I know which one to choose? And what does (QA) mean?
5. ### Kinetics question

Homework Statement I trying to do this hibbeler question which I have modified a bit However I'm not getting the correct answers which is supposed to be t=17.5 and t=11.3 s I will take a picture of my attempt when I get a hold of a camera in the meantime if anyone knows how to do it I...
6. ### Engineering Thevenin equivalent circuit

a 15.81 voltage power supply connected to a 25ohm resistor?
7. ### Engineering Thevenin equivalent circuit

so do i use P=(V^2/R) or P=I^2*R if i use P=(V^2/R) i get V = sqrootof(25*10)=15.81V if i use P=I^2*R i get I=sqrootof(10/25)=0.632A V=R*I=15.81V Then I=V/(RL+RS)= 15.81/(25+5)=0.527A are my calculations correct?
8. ### RC network

Two 500μF capacitor are connected in parallel, and then to a 100kW (105W) resistor. The capacitors are momentarily charged using a 1000V D.C. supply. Find: a) The time constant of the circuit. b) The time “t” taken for the capacitor voltage to decay to 630 volts c) The current in the...
9. ### Define the term Speed

Explain why “Torque-Speed” matching is important in designing motor-driven machines. Illustrate your answer with torque-speed plots characteristic of: i) A fan load ii) A high static friction load ?!?1?111one
10. ### Define the term Speed

electronics question Define the term “Speed” as employed in rotating machines, and state its (S.I) units. anyone know the answer? is it rad per second?
11. ### Engineering Thevenin equivalent circuit

Homework Statement A variable resistor (RL) is connected to an unknown circuit. It is found that the maximum power that can be dissipated in the resistor (RL) is 10W, and that this occurs when the value of the resistor (RL) is 25ohms. Derive the Thevenin equivalent circuit for the unknown...
12. ### Phase Angle

An inductor “L” is connected in series with a Resistor “R”. This circuit is connected to a sinusoidal voltage “V”, and a current of 1A flows. If the circuit resistor has a value of 1W, and the magnitude of the reactance of the inductor “L” is 1W at the supply frequency, state: (i) The...
13. ### P-N junction

ok well since i have the mean voltage, rms voltage and peak voltage can i no just use V/R=I so Vpk/1000ohms=Ipk then do the same for the rest of them?
14. ### P-N junction

1000w should be 1000ohms Vpk=25/1000=0.25A Vrms=25/sqroot2=17.68v Irms=17.68/1000=0.0177Arms Vmean=Vrms*0.9=15.9V Imean=15.9/1000=0.016Amean Are these result and equations correct? sry don't have a scanner so can't post sketches
15. ### P-N junction

Show how two P-N junction diodes can be used in conjunction with a transformer that has two secondary windings, to form a full-wave rectifier. (Draw a circuit diagram including connections to the mains transformer). Explain the operation of your circuit using sketches of waveforms. (3 marks)...
16. ### Find the value of z

how do i find z in this problem -10z+(z-1)21.875-[(z-1)5*((2-1)/2)]=0 i get a quadratic equation but can't seem to get the right answer z=2.094
17. ### Maximum bending moment in aluminium alloy beam

yeah thanks for the reply sorted it out now
18. ### Maximum bending moment in aluminium alloy beam

I have three questions and need to calculate the magnitude of the maximum bending moment 1) A 4 m long aluminium alloy beam, simply supported at its ends, carries a central concentrated load of 2 kN. The T-cross-section of the beam (see Figure A2) consists of a rectangular flange and web...
19. ### Solid Shaft shear stress

oh T=30000/(500*(pi/30))
20. ### Solid Shaft shear stress

ok well could u tell me what i should do
21. ### Solid Shaft shear stress

Homework Statement A solid circular steel drive shaft is 4 m long and 60 mm diameter. The modulus of rigidity of the steel is 85 GPa and its maximum allowable shear strength is 150 MPa. The shaft is used to transmit a power of 30 kW while rotating at 500 rev/min. Calculate the following...
22. ### Hollow shaft torsion

So what should I do to get the correct answer? r=500^4-475^4 ? what should it be instead of 10^6 ?
23. ### Hollow shaft torsion

Homework Statement A turbine shaft is to transmit power at 240 rev/min. If the shaft is 1 m external diameter and 25 mm thick and the maximum shear stress is limited to 69 MPa, find the power transmitted. Homework Equations The Attempt at a Solution T=J*stress/r =...