[Kosmos]

I can vouch for Feynman. He is fantastic at what he does and I can assure you that he will help you with any question you may have.

[i like soccer]

I PMed you with some questions yesterday. Can you please help?

[i like soccer]

I'm very busy today. I'm trying my best to help as many people as I can, but I have some other things that I have to get done before I go away on Saturday.

Sure thing. Get to me when you can, then.

[Area 51]

what is the difference between ac generator and dc generator?

[Area 51]

DC Generators produce a direct current, one that travels in one direction through the circuit, kind of like a race car on a track.

AC Generators produce an alternating current, which changes its direction many times per second. It's a bit harder to picture, but you can almost thing of it as a person going back and forth on a swing.

Oh wow, and yea it is pretty difficult to picture. :S

[Area 51]

Here's a better analogy I found:

Imagine you have a series of pipes, connected together into a loop. The pipes are filled with water, which is being pumped through the pipes in one direction. After a certain amount of time, the pump reverses, pushing the water in the opposite direction. Here's a diagram I made to help you:

Thank you so much sir . Appreciate your help :)🎉

[Area 51]

Why is electricity transmitted using AC currents and not DC currents ??? Please help me out with this

[Area 51]

There are a few advantages to AC current versus DC.

1) AC can travel through long circuits for efficiently

2) AC also allows for high voltages to be used more easily. With an AC circuit, you can use a transformer to easily amplify the voltage, but transformers don't work with DC.

Alright, appreciate your help a lot man, thanks!

[iLuvHackForums]

Physics help please!
Ross in his Bugatti Veyron Super Sport rolls across a starting line at 25 mph. ¼ mile later he is going 248mph. This takes him 9 seconds. What is his average acceleration in Meters per second? There are 1.1 yards in 1 meter and 1769 yards in 1 mile. Show all of your work

[iLuvHackForums]

I dont understand any of these problems. Can some one help me out?
1. If the designer has 12 outfits to choose from, how many ways are there to arrange the order in
which he will show ten of them?

2. The community 10K run/walk event awards ribbons to the top four finishers in each age
category. If 20 people in the 15-19 age range register for the race, how many ways are there
to arrange the top four finishers?

3.A new computer store offers a special early-bird prize give-away for its grand opening. The
first 12 customers to enter the store between 7 a.m. and 8 a.m. will receive gift certificates
worth various dollar amounts. If 18 customers gather to enter the store between those hours,
how many ways are there to arrange the twelve prize winners?

4.A state university issues five-digit student identification numbers to all of its students. None of
the identification numbers contain the digit 0 and the digits cannot be repeated. How many
ways are there to arrange five digits if only the numerals 1 through 9 are used?

[360]

A force F = (6i-2j) acts on a particle that undergoes a displacement of r=(3+j) metres. Find (a) the work done by the force on the particle and (b) the angle between F and r.

I've already done part (a) and found the work done to be 16J, just need to know how to find the angle between the vectors.

[360]

I assume you mean 3i?

Difference = r-F = (3i+j)-(6i-2j)=(-3i+3j) or (-3,+3)
tan^-1(Rise/Run) = Angle.
tan^-1(-1) = angle = 45(o)

Cheers for that mate, seems straightforward enough

[img]http://www.webassign.net/sercp/p5-55alt.gif[/img]

If I want to find the work done in a graph like this, do I simply create a triangle under the line and find the area?

And if I wanted to find the total work done from x(initial) to x(final), do I add the areas above and under the x axis to find the work done (so I am actually subtracting the area under the x axis)?

[360]

No worries, got that. Thanks.

Some more for you guys, if you don't mind;

-Question 1-
A 7.80 g bullet moving at 575 m/s penetrates a tree trunk to a depth of 5.5 cm. a) use work and energy considerations to find the average frictional force that stops the bullet. b) assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.

-Question 2-
A 0.600-kg particle has a speed of 2.00m/s at point A and kinetic energy of 7.50 J at point B. What is (a) its kinetic energy at A? (b) Its speed at B? © the total work done on the particle as it moves from A to B? (Part C is the part that is bothering me here, not so much (a) or (b). Do I just take the average force (force at point A and force at point B and divide by 2? So I can use that force in the W=FxD equation?)

-Question 3-
A 2100 kg pile driver is used to drive a steel I-beam into the ground. The pile driver falls 5 m before coming into contact with the top of the beam. Then it driver the beam 12 cm farther into the ground as it comes to rest. Using energy considerations, calculate the average force the beam exerts on the pile driver while the pile driver is brought to rest.

[360]

A backyard swimming pool with a circular base of diameter 6.00 m is filled to depth 1.50 m.

A) Find the absolute pressure at the bottom of the pool. (Done, but including it so as to understand the entire scope of the question). Answer is 115.7 kPa

B) Two persons with combined mass 150 kg enter the pool and float quietly there. No water overflows. Find the pressure increase at the bottom of the pool after they enter the pool and float.

No idea where to start with part B, since to use p=m/v I need the volume, but since I need h in the volume (which has changed) I'm not really sure.

[360]

There's actually a much easier way to do it!

P = F/A = mg/A = (150)(9.81)/(9π)

Your answer is the increase in pressure, so the new absolute pressure is your answer from (a) + (b).

Makes a bit more sense...but where did you get 9pi from?