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A 20 - pound electric motor is mounted on 3 vertical springs, each having a constant stiffness of 10 pounds per inch. Compute the period with which the electric motor vertically vibrates.

There are n couples at a party. Each man shakes hands with everyone else except his spouse. No handshakes take place between any woman. How many handshakes take place? (as a polynomial function of n)

Draw the power circuit and design the control circuit for a three stage primary resistance with forward and reverse.

If my question is about the effectiveness of a certain design (Is it effective or not?), what should I use: 1 -tailed test or 2 - tailed test? Thank you in advanced!

How can I improve the way the solar batteries absorb light from the Sun in order to convert it to electrical energy?

http://www.treehugger.com/clean-technology/water-t...

We are now making this water system but "improvements" must be made. What are the improvements that can we make here? Thanks!

Can you please describe what is this code: EP 2 557 407 A2 all about? Thanks!

what are the current unsolved problems in electrical engineering? pls help me. thanks!

1.) In a factory, the ratio of the number of male to female workers is 2:3. If 100 new female workers are hired, the number of female workers will increase to 65% of the total number of workers. Find the original number of workers in the factory.

2.) A job could be finished in 150 days if 50 men are working full time. 60 men started working on the job and after 20 days, 20 more men are added. But after 80 days, 50 men quit the job. How long could it take for them to finish the job?

A box contains six blue socks and four white socks. Find the number of ways in which can two socks be drawn from the box where (a) there are no restrictions (b) they are different colors (c) they are of the same colors. Thank you! :D

1.) Assuming a bac sequence, determine the line currents of a 3-phase load having an apparent power of 4500 VA and 0.73 power factor lagging.

2.) With the same apparent power and power factor in 1.), if the sequence is now in cn-an-bn, determine the said load's line currents.

1) Find the voltage V across the inductor at t=0, if L = 20mH and:

a) I(t) = 20 e^(-30t) cos(500t) A

b) the stored energy is e^(-800t) J and I(0)>0

2) Find the current through the 20mH inductor at t=0 if:

a) I(-1) = 2A & V(t) = 2t^3 V

b) the stored energy is 4J at t=0, I(0)>0 & V(t) = 6sin120t V

solve a and b separately. tnx! :)

a tank is filled with 2 pipes. the first pipe can fill the tank in 10 hours. But after it has been opened for 3 and 1/3 hours, the second pipe is opened and the tank is filled up in 4 hours more. how long would it take the second pipe alone to fill the tank? the two pipes have different diameters.

A child, searching for his favorite fave wooden horse, is running on the ground around the edge of a stationary merry-go-around. The angular speed of the child has a constant value of 0.25 rad/s. At the instant the child spots the horse, one-quarter of a turn away, the merry-go-around starts to move (in the direction of the child is running) w/ a constant of 0.01 rad/s^2. What is the shortest time it takes for the child to catch up w/ the wooden horse?

A 500 KVA transformer has a 0.6 lagging power factor load of 280 KVA. (a) If additional 0.8 power factor lagging loads are to be added, how many KVA of such loads can be added without overloading the transformer? (b) A 0.8 lagging power factor load of 300 KVA is to be added. Will the transformer be overloaded? (c) If the answer to (b) is yes, determine the KVAR of capacitors needed to reduce the load on the transformer to its rated value.

A series circuit consisting of a 10 ohm resistor, a coil and an ideal capacitor is connected across a 200 V, 60 Hz power supply. The current drawn is 8 A. The voltage across the coil is 120 V and its power factor is 0.8 lagging. Determine (a) the capacitance of the capacitor, and (b) the resultant voltage across the resistor and the coil.

A series circuit consisting of a 10 ohm resistor, a coil and an ideal capacitor is connected across a 200 V, 60 Hz power supply. The current drawn is 8 A. The voltage across the coil is 120 V and its power factor is 0.8 lagging. Determine (a) the voltage across the capacitor, (b) the resultant voltage across the resistor and the coil, and (c) the capacitance of the capacitor.

A series circuit consists of a coil, a resistor and a capacitor connected across a 250 V, 60 Hz power supply. The voltage across the coil is 150 V, that across the resistor is 100V and that across the capacitor is also 100 V. THe resultant voltage across the coil and the resistor is 200 V. If the circuit draws 15 A from the source, determine (a) resistance and inductance of the coil (b) the resistance and capacitance of the capacitor.

Given points a(2, 5, -1), b(3,-2,4) & c(-2,3,1).

Find:

(a) Rab "dot" Rac

(b) angle between Rab and Rac

(c) the length of the projection of Rab on Rac

(d) the vector projection of Rab on Rac