BF2S Forums Homework Help Thread

hah you're doing homework over spring break

Seems to me like you need to know the distance between the styrofoam and the sheet. The only thing would be if you knew the permativitty of styrofoam, maybe you could use that with the charge to get the flux and go from there. I can't think of why else they would tell you it's styrofoam.

Alright guys, I'm desperate.

I have an essay for a political theory class (non-elective) on The Republic in comparison to Locke (Letter Concerning Toleration) regarding the treatment of religion. My problem is more-so with Plato's (or Socrates, or Plato's Socrates) treatment of religion than anything, although help with either would be appreciated.

Specifically, what is the problem posed by Homer and Hesiod's representation of the gods in relation to political life? Why is Plato concerned with the implications of their religion?

Now I understand that he views religion as a socializing agent to be exploited for political function and civil harmony, but what EXACTLY is the goal of the new religion, and what are the problems posed by the old one?

No, this is not just the essay question- it's just the first paragraph. I. AM. Fucked.

EDIT- I suppose I should go ahead and tell you specifically what I am looking at:

         Books 2 and 3 in The Republic of Plato are the most direct view of his views on religion (I am not allowed to use any other works). If there is a better section for looking at religion within The Republic, that would also be extremely helpful.

Last edited by Pochsy (2010-03-20 12:55:13)

I need information about hydrogen fuel cell cars. Videos, articles, anything. Tried wikipedia, wasn't satisfied. Cheers

Que?

GmM/r^2=mv^2/r

tbh

3. Calculate work required to move a planet's sattelite of mass (m) kg from a circ orbit of radius 2r to 3r. Mass and radius of planet are given.

4. (m) kg satellite circles earth with period T = 95min. Radius/mass of earth given. Find Energy required to change the orbit to period T = 171min.

13. Sand falls from a hopper onto a conveyor belt at (m) kg/s, the belt is moved by rollers at (v) m/s. Find frictional force on sand by belt.

18. A chain mass (m) kg and length 9m is on a table. Half of the length is over the side. Assume frictionless. The chain is let go. Find the magnitude of the velocity of the chain when 6.3m is hanging vertically (this is a 2 parter, I already found the acceleration of the chain at that time)

20. A (m) kg rocket travels (v) m/s to the moon. It's found to have drifted off course and must change direction by 9.6degrees. Gasses are expelled perpendicular to the rocket's motion at (v2) m/s. What mass of the gas was expelled?


side note: the stuff in parenthesis I have values for, but scholastic dishonesty etc.

for 3 and 4 I tried using formulas for potential energy and period respectively. For 13, I'm completely boggled. For 18, I tried integrating the acceleration but that didn't work out. For 20, this one gives me a headache. I tried separating the rocket's velocity into x and y components (as laid on a grid), and then multiplying by mass, then dividing by the velocity of the rocket fuel, and then dividing by sin80.4, but that didn't work either.

20 is just a 2D conservation of momentum problem.
Momentum of Rocket + Momentum of Gas Expelled = Momentum of Rocket on New Path
m*v (vertical-Direction) + m*v (horiz-direction) = m*v (diagonal direction)

To solve take the Momentum of The Gas Expelled = The horiz portion of the Momentum of the Rocket on the New Path
m*v = m*v*sin(9.6degrees)

I'm assuming you have all the numbers for that equation?

WldctARCHe wrote:

20 is just a 2D conservation of momentum problem.
Momentum of Rocket + Momentum of Gas Expelled = Momentum of Rocket on New Path
m*v (vertical-Direction) + m*v (horiz-direction) = m*v (diagonal direction)

To solve take the Momentum of The Gas Expelled = The horiz portion of the Momentum of the Rocket on the New Path
m*v = m*v*sin(9.6degrees)

I'm assuming you have all the numbers for that equation?

Yeah. But the gas expelled is perpendicular to the slightly-off motion of the rocket, it's not purely in the horizontal direction... which should mean I break that up into components as well, which I already did.

WldctARCHe wrote:

If the gas is expelled perpendicular to the rocket then it doesn't matter.  Set your coordinate system to make the gas the horizontal axis and the path of the rocket in the vertical direction.  Thus this means you only have to take the components of the rocket after gasses are expelled.

This gives me my first answer which was incorrect.

5700(3200)sin9.6 = 4700(m)

m = 647.2kg

mass = 5700kg, traveling at 3200m/s initially

gases are expelled at 4700m/s

I don't have the answer, it's a submit form online with multiple tries.

WldctARCHe wrote:

Do you know the final velocity of the rocket...because if you don't then technically the problem would be unsolvable without making some assumptions somewhere?

Um... no idea.

WldctARCHe wrote:

Just curious try 956.9 kg for the mass...made some assumptions...if it works i'll explain it...

nope

i'm not really bothered, i've used up pretty much all my guesses already anyway

bleh

WldctARCHe wrote:

Okay, sorry I couldn't help.  Good luck with the rest of it!

Thanks. If nukchebi is still out there somewhere, I got 13. I think 3 and 4 could be pretty easy, I'm just applying the wrong formulas or something.