12 replies to this topic

[ilovepolkadots]

this isn't so much physics as algebra, but really i suck at math

sooooo ... help O.O



formula of the gods::






another question that fucks my mind....




....
<.<
>.>

Edited by ilovepolkadots, 13 December 2011 - 01:38 PM.

[thorgal]

F= 74kg+3,9kg * 9,81 N/kg

A= (6,5m)^2*pi

you can do the math yourself

Edited by thorgal, 13 December 2011 - 01:45 PM.

[ilovepolkadots]

Pressure = Force / Area

Force = Mass * Acceleration


....

Force = (74kg +3.9kg) * (9.81m/s^2)
F = 655.995 Newtons

Pressure = (655.995N)/(2pi x 0.0065m)

P = 16062... not really sure of the units (Pa? ) lets see!

totally didn't square the radius
x.X

i got 2471120.6
two sig figs = 2,500,000

still wrong

okay....

so the F = 77.9 * 9.81 = 746.199N
A = 2pi*(.0065m^2) = 2.65E-4

Pressure = 2878421.68
two sig figs.... 2,900,000
still wrong

ah HA!
by EACH leg of the chair

i just need to divide by four


1 Pa = 1 kg/(m·s²)
so i divided by four.... and got 719,605
reduce to two sig figs.... 720,000 and that was also wrong


two more submissions left for this question x.X

[glitch]

According to my physics textbook that I thought I would never have to pick up again after dropping the course, that formula of the gods can be rewritten as:

I = I(0) x 10 ^(beta/10 dB).

I'm not exactly sure if that's what they're looking for, but it's all that I got. ...By any chance, is that screenshot from MasteringPhysics?

[ilovepolkadots]

According to my physics textbook that I thought I would never have to pick up again after dropping the course, that formula of the gods can be rewritten as:

I = I(0) x 10 ^(beta/10 dB).

I'm not exactly sure if that's what they're looking for, but it's all that I got. ...By any chance, is that screenshot from MasteringPhysics?

i will try it out :3

and oh yes - matering physics indeed
what is particularly terrible is that our professor confessed today that he just picks the questions at random
so even though i go to every lecture there is still a 70% chance what is in the homework was not covered/explained in class
-.-

and that was correct

you are awesome

also sort of my soulmate
as i have also dropped physics (twice)
this is my second to last semester at uni so i literally have to take it
aaaaand physics 105 next semester *murders self*

[glitch]

You're welcome. <3

Urgh, I took it this semester....realized I didn't need it, dropped it in a heartbeat. Best decision of the semester. I'd try the second question, but I don't trust my physics...and I need to rewrite the Algebra II question someone wrote on the forums and then actually study for my own final tomorrow (ahhhhhh).

[ilovepolkadots]

You're welcome. <3

Urgh, I took it this semester....realized I didn't need it, dropped it in a heartbeat. Best decision of the semester. I'd try the second question, but I don't trust my physics...and I need to rewrite the Algebra II question someone wrote on the forums and then actually study for my own final tomorrow (ahhhhhh).

no worries :3
i appreciate you taking the time for the one question!
& good luck with your finals!!

[glitch]

Although, I did notice something that might make a difference:

Area of a circle = pi* r^2

The question gives you diameter in centimeter, so it would be actually 0.0065m in radius. So the area would be 0.00004225pi of each leg. So, overall area would be 0.00004225pi * 4.

Which would make it:

Pressure = Force/Area

(74+3.9)*9.81/ (0.00004225pi*4) = Total Pressure so in order to find individual pressure on each leg, it would be:

[(74+3.9)*9.81/ (0.00004225pi*4)]/4 = Pressure on each leg.

I got 359840.3798 which when rounded to 2 sig.figs. should be 360000 Pa.



...I think. Take with a grain of salt! (Okay, time to actually do organic chemistry now).

[Waser Lave]

Shouldn't it be:

((74+3.9)*9.81)/(4*pi*((0.013/2)^2))

Which would be 1400000 to 2sp.

[Leaf]

just google it. I google everything... even my cerial

[ilovepolkadots]

Area of a circle = pi* r^2

(^) this was my problem
x.X ( i am so dumb)

and i ended up working it out last night and the answer was::
1.4×10⁶ Pa

after talking to my roommate though he said that it was not realistic what i did
which was solve for the total pressure and then divide by four
~.~

and then was a biatch and said if you put 100 monkeys in a room with typewriters eventually one would write Shakespeare


anywho i appreciate the help from both of you !

Shouldn't it be:

((74+3.9)*9.81)/(4*pi*((0.013/2)^2))

Which would be 1400000 to 2sp.

(^) see Waser thinks the right way
i do not - you are finding the area of ONE leg in order to find the pressure that one leg exerts

& again thank you to both of you !

[luvsmyncis]

I haven't been to school in 8 years, so when I see stuff like this, I feel like...

[ilovepolkadots]

I haven't been to school in 8 years, so when I see stuff like this, I feel like...

lolz
xD

my physics lab TA is pretty awesome and gives credit for funny answer
which is nice since that is all i got x.X