Can I Use My Calculator for the Upcoming Physics Exam?

  • Thread starter Thread starter Alt+F4
  • Start date Start date
  • Tags Tags
    Exam
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
Sign up Log in
66 replies · 7K views
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa02

Why is Question 11 C??
 
Last edited by a moderator:
Physics news on Phys.org
All right last question and i think i will be done
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa02

Question 5

Force = VB sin theta

but there is all this other stuff,

so i did
Force = A*V*B*R / (T) = .001 so why am i off by a factor of 10^-2. Thanks for everyones help
 
Last edited by a moderator:
Alt+F4 said:
Exactly, except for the Phasor i put in the Angle
Put your calculator in radian mode and enter the phase angle in radians.
 
OlderDan said:
Put your calculator in radian mode and enter the phase angle in radians.
Nope.i get 1.7E-9, 2.2E-8 unless i have to convert it somehow
 
Alt+F4 said:
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/sp06

Question 11

I wanted to use this formula B = UoI/ 2 pi R but i have no idea how to use it cause i keep getting a big number
That is not the formula you need. That is for finding the field produced by a current in a wire.

The induced emf is the negative of the rate of change of flux through the loop. Flux is related to field strength and area. The field is constant. The area is changing at a constant rate. The current is related to the induced emf and resistance of the loop.
 
Last edited by a moderator:
OlderDan said:
That is not the formula you need. That is for finding the field produced by a current in a wire.

The induced emf is the negative of the rate of change of flux through the loop. Flux is related to field strength and area. The field is constant. The area is changing at a constant rate. The current is related to the induced emf and resistance of the loop.
o yaaaaa thanks a lot
 
Alt+F4 said:
one more,

http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/sp06

question 24.

i did this like 20 times in other exams, i don't know why it doesn't work here but

F= ILBSintheta = MG

(X)(.1)(.5) = (9.8)(1)
X = 196Amps, but the answer is 98 Amps what gives?
all right so why am i only counting current for one side icne 196/2 = 98
 
Last edited by a moderator:
Alt+F4 said:
Nope.i get 1.7E-9, 2.2E-8 unless i have to convert it somehow
You are doing something wrong in your calculator. If the current and voltge were in phase you would have a maximum power of 120V*5A=600W. The phase difference reduces this somewhat, but not by a huge amount.
 
OlderDan said:
You are doing something wrong in your calculator. If the current and voltge were in phase you would have a maximum power of 120V*5A=600W. The phase difference reduces this somewhat, but not by a huge amount.
hmm well i think there is something wrong with their calculation, i have no idea how they got 25 Degrees to .436 radians, i got .4663 radians so maybe that is why i can't get their answer
 
Question 16 please :)
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa05


So i tried doing it on Calculator but since sin180 = 0 i get 0
 
Last edited by a moderator:
Alt+F4 said:
hmm well i think there is something wrong with their calculation, i have no idea how they got 25 Degrees to .436 radians, i got .4663 radians so maybe that is why i can't get their answer
25/180*π = .43633 not .4663
 
OlderDan said:
25/180*π = .43633 not .4663
ya i can't get the answer at all, i tried on diffrent calculators. i am postiive I am typing it correctly
 
Alt+F4 said:
ya i can't get the answer at all, i tried on diffrent calculators. i am postiive I am typing it correctly
Are you using the calculator to find the maximum of the product IV? How are you doing this?
 
i went to Y = and type in that whole equation, then hit Graph, then did 2nd Graph and found the maximum value
 
Alt+F4 said:
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa02

Why is Question 11 C??
is there an explanation for this one or is this one of the thing you memorize
 
Last edited by a moderator:
Alt+F4 said:
i went to Y = and type in that whole equation, then hit Graph, then did 2nd Graph and found the maximum value
When I do that I get 571.9W using their value of 0.436 for phase in radians, which is correct. What do you get?
 
Alt+F4 said:
Question 16 please :)
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa05


So i tried doing it on Calculator but since sin180 = 0 i get 0
It is not sin180. It is sin180t with t constantly changing. You need to find the maximum rate of change of the flux and use the number of turns to find the maximum emf.
 
Last edited by a moderator:
Alt+F4 said:
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa02

Why is Question 11 C??
Did you find the current in the circuit? Did you compute the voltages for each of the elements from that current?
 
Last edited by a moderator:
Alt+F4 said:
Last Question of the day i promise :), thanks for everyones help

http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa05

Question 3

Why is it just (3)(.7*.2*2) = .084 Why not take into account the left side. Thanks
This is from the left side. It is the only side in the magnetic field. The right side contibutes nothing.
 
Last edited by a moderator:
OlderDan said:
When I do that I get 571.9W using their value of 0.436 for phase in radians, which is correct. What do you get?
same but the answer is 543 that is why I am so confused
 
Alt+F4 said:
one more,

http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/sp06

question 24.

i did this like 20 times in other exams, i don't know why it doesn't work here but

F= ILBSintheta = MG

(X)(.1)(.5) = (9.8)(1)
X = 196Amps, but the answer is 98 Amps what gives?
is this the same idea on how one side isn't really contibuitng?
 
Last edited by a moderator:
Alt+F4 said:
is this the same idea on how one side isn't really contibuitng?
I thought you had already resolved this one (#24). For this one you only used one side of the loop when you should have used both sides. Both sides contribute to the torque, so only half the current you calculated is needed.
 
Last edited:
OlderDan said:
I thought you had already resolved this one (#24). For this one you only used one side of the loop when you should have used both sides. Both sides contribute to the torqe, so only half the current you calculated is needed.
silly me, thanks a lot for your help like seriously. My TA's arent even that helpful
 
Alt+F4 said:
Question 16 please :)
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa05


So i tried doing it on Calculator but since sin180 = 0 i get 0
hmm all right so i graphed this, Does it matter if calc is in radian or degree?
 
Last edited by a moderator:
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/su06

Question 20
Finger Curl with current
B Field points Down

I woulda picked Rotates it so that the right side comes out of the page and the left goes in.
 
Last edited by a moderator:
All right last question until Nov 23rd i think

http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa03

Question 21


So W = 2piF = (2*3.14*580*10^3) = 3.6E6
>and 1 / ( sqrt 1*10^-3 * .06*10^-6) = 1.2909 E5

what am i doing wrong
 
Last edited by a moderator:
Alt+F4 said:
All right last question until Nov 23rd i think

http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/fa03

Question 21


So W = 2piF = (2*3.14*580*10^3) = 3.6E6
>and 1 / ( sqrt 1*10^-3 * .06*10^-6) = 1.2909 E5

what am i doing wrong
You are supposed to be finding the value of C that will make the resonant frequency of the circuit the desired broadcast frequency. How does C affect the net capacitance of the circuit?
 
Last edited by a moderator:
Alt+F4 said:
http://online.physics.uiuc.edu/cgi/courses/shell/phys102/fall06/prep2a.pl?practice/exam2/su06

Question 20
Finger Curl with current
B Field points Down

I woulda picked Rotates it so that the right side comes out of the page and the left goes in.
Currents parallel to magnetic fields experience no force. Currents at right angles do.
 
Last edited by a moderator:
Alt+F4 said:
hmm all right so i graphed this, Does it matter if calc is in radian or degree?
Yes. Always use radians for these time dependent problems. If they ask for phase in degrees, convert it from radians. If they give phase in degrees, convert it to radians. Angular frequency is always in radians/sec.
 
OlderDan said:
Yes. Always use radians for these time dependent problems. If they ask for phase in degrees, convert it from radians. If they give phase in degrees, convert it to radians. Angular frequency is always in radians/sec.
all right but for some reason when i graph in Radian mode i seriously get like -6 and -5 values unless i am doing something wrong with it
 

Similar threads

Programs Can I Use My Chemistry Background for Research in Physics?
  • DrTherapist
  • · Replies 22 ·
  • STEM Academic Advising
Replies
22
High School Can I use a Calculus application on my calculator for the AP Calculus AB test?
  • Cursed
  • · Replies 1 ·
  • Calculus
Replies
1