09-17-2004, 12:31 PM #1
PLEASE HELP!! w/ physics problem...
Alright, I know there are some smart fckers on here. I need yea guys to lend me a hand here. I have some stupid physics assignment due this evening, but I havent bought the book yet and Im stumped on the last two problems. I think i can get one of them, but here is the other.
Two equally charged particles, held 3.1 10-3 m apart, are released from rest. The initial acceleration of the first particle is observed to be 8.0 m/s2 and that of the second to be 10.0 m/s2. The mass of the first particle is 6.3 10-7 kg.
(a) What is the mass of the second particle? (in kg)
(b) What is the magnitude of the charge of each particle? ( in C )
Thanks in advance,
09-17-2004, 12:37 PM #2
id help but im unclear about your 3.1 10-3m and the 6.3 10-7kg, what the heck is that.
09-17-2004, 12:39 PM #3
open up your physics book and find the answer. i took 1 class as a elective and hated it.
09-17-2004, 01:00 PM #4
F = k(q^2)/r , F = m*a , q^2 since they are both equally charged
8.0(6.3E-7)=k(q^2)/3.1E-3 where k = 8.99E9
1.5624E-8=8.99E9(q^2), q^2 = 1.73793E-18, q= 1.31831E-9
b) q = 1.31831 x10^-9 C
a) 10(m) = 8.99E9(1.31831E-18)/3.1E-3 , 10m = 5.04E-6, m = 5.04E-8 kg
i think thats right, if i remember coloumbs law correctly.
Last edited by Psychotron; 09-17-2004 at 02:21 PM.
09-17-2004, 01:11 PM #5
A. F1 = F2... M1*A1 = M2*A2 ... So Simple!!!
B. Use Coulombs Law, q1 = q2. Just solve for q.
You really need to try harder. This is first year crap! Have fun.
09-17-2004, 01:21 PM #6
wtf? e=mc2......maybe? i am glad i stuck with american history and accounting
09-17-2004, 01:21 PM #7
yea psych. those are the correct formulas. Thanks for the help it seems correct. And you guys are correct, it is easier crap that I should know. This whole first two weeks is mostly review from the previous ph. class, but i forgot alot over summer.
I also have not bought the physics book yet for me to read, I have to wait until my next paycheck before I can afford the other half of my books, so until then im stuck.
Thanks for the help,
09-17-2004, 01:24 PM #8Originally Posted by Psychotron
dam.....beat me to it......
09-17-2004, 01:41 PM #9
actually, i noticed psyc. formula is wrong.... you didnt square the distance r
F = [K(q1)(q2)/r^2]*[r_vector] I understand that vectors do not matter in this problem, but i just posted the complete formula anyways.
I also did it this way before i originally posted, but I got the wrong answer so thats why I posted. I dont know if im entering it in wrong or what?
BTW, i am using the F = ma, so ma = K*q^2/r^2
I enter the answers on webassign, so i know if they are correct or not right away
Last edited by OSTIE; 09-17-2004 at 01:44 PM.
09-17-2004, 02:10 PM #10
oh, yea the vectors supposed to be squared. i last took physics a year ago lol
my numbers arent the same as what mac was saying. im not sure who is right. i assumed the coloumbs equation since they give you a vector distance.
so even with the r^2 the answer is wrong?
8.0(6.3E-7)=k(q^2)/(3.1E-3)^2 where k = 8.99E9
4.84344E-11=8.99E9(q^2), q^2 = 5.38758E-21, q= 7.34E-11
b) q = 7.34 x10^-11 C
a) 10(m) = 8.99E9(5.38758E-21)/(3.1E-3)^2 , 10m = 5.04E-6, m = 5.04E-8 kg
F1 = F2 , M1*A1 = M2*A2 8(6.3E-7)=10M2 , M2 = 5.041E-8kg
our masses line up.
note: i screwed up in my first time on the mass and later edited it when i saw the mistake when i did the calculations with the vectors squared.
Last edited by Psychotron; 09-17-2004 at 02:24 PM.
09-17-2004, 02:27 PM #11Originally Posted by Psychotron
Finally got the force correct, I had the power one off, i tried your power and it was right. I need a friggin ti-89, im stuck using a plain old calc.
ANYWAYS, the mass one doesnt seem to be correct... webassign though is a pain, because sometimes if you round off to early, you will be a hundreth off and itll be wrong.
09-17-2004, 03:04 PM #12
both of our ways are valid for finding the mass, its not possible for it to be incorrect.
Last edited by Psychotron; 09-17-2004 at 03:39 PM.
09-17-2004, 03:41 PM #13
well it wont let me edit it so here. i did both way in one step on my ti-89 and the mass for both comes to 4.8E-7 kg
09-17-2004, 03:48 PM #14Junior Member
- Join Date
- May 2004
i respect the question and the fact that you recieved a legitimate answer.... now who wants to take my genetics test for me next week?
09-17-2004, 04:03 PM #15Originally Posted by Psychotron
5.0e-7 is what the friggin website took as an answer. I hate this friggin software that they use for us to submit answers.
Thanks for the help, it is greatly appreciated,
09-17-2004, 04:53 PM #16Originally Posted by SAUCYgator
09-17-2004, 10:43 PM #17Originally Posted by SAUCYgator
I'll take it...let me know when and where....I ain't sceered!!!!
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