physics mcq help needed! urgent!

[ruby92]

can someone please help me with m/j 2003
3 18 22
 

[cashem'up]

I have a question myself, nov05 question 5
answer should be D but its C

your supposed to add the uncertainties which means its 0.1+(0.01*3)= 0.13
anyone help??? cause this is not the answer

no i am pretty sure its C , whenever u r calculating uncertainties if its multi or division........u have to percentage uncertainties so
0.1/25 x 100 = 0.4%
0.01/5 x 100 = 0.2%
0.01/2 x 100= 0.5%
0.01/1 x 100 = 1%

now u add these so u get 2.1%......however we want in decimal
so 2.1/100 x 2.5= 0.0525

hope it helped
 

[halosh92]

can someone please help me with m/j 2003
3 18 22
 

Q3
use the cosine rule , the angle would be 60
so
resultant= sqrt [10^2+10^2-(2*10*10*cos60)]
=10

[astarmathsandphysics]

6 D V=IR to get R=8 then add the uncertainites 20%+5% =25% of 8 +-2
Not technically the right way to do it.
11. D elastic so separation speed = approach speed and momentum conserved o
only possible answer is d

[halosh92]

can someone please help me with m/j 2003
3 18 22
 

Q18
v^2=u^2+2as
0= 10^2 + 2 * -a* 10
(a is negative as its decelrating)
a=5m/s^2
same force means same acceleration so:
same equation we use, but instead of u we put 30 and instead of "a" we put 5
u will get 90m which is D

[halosh92]

6 D V=IR to get R=8 then add the uncertainites 20%+5% =25% of 8 +-2
Not technically the right way to do it.
11. D elastic so separation speed = approach speed and momentum conserved o
only possible answer is d

thankyou but for Q11 could u explain in detail ..how to apply this theory?

[halosh92]

2009 nov second variant Q12

june 2005 Q22
nov 2008 Q24

[[Spy]]

no i am pretty sure its C , whenever u r calculating uncertainties if its multi or division........u have to percentage uncertainties so
0.1/25 x 100 = 0.4%
0.01/5 x 100 = 0.2%
0.01/2 x 100= 0.5%
0.01/1 x 100 = 1%

now u add these so u get 2.1%......however we want in decimal
so 2.1/100 x 2.5= 0.0525

hope it helped
 

oh so you have to reverse it at the end! yeah thats my mistake!

thanks

[ruby92]

Q3
use the cosine rule , the angle would be 60
so
resultant= sqrt [10^2+10^2-(2*10*10*cos60)]
=10

why is the angle 60?

[halosh92]

why is the angle 60?

becaus ei have to imagine the same line on the other side, which makes it parallel, parallel lines: their interior angle add up to 180
so 180-120=60
trignometry u will have to imagine a triangle and use the cosine formula there

[ruby92]

becaus ei have to imagine the same line on the other side, which makes it parallel, parallel lines: their interior angle add up to 180
so 180-120=60
trignometry u will have to imagine a triangle and use the cosine formula there

thnkx alot
 o/n 2003 24 31

[halosh92]

thnkx alot
 o/n 2003 24 31

np
ok Q24
just draw 6 lines imagine each as a node, count the spaces between the line  they are 5 spaces
30/5 = 6cm
so 6 is one space  , the distance form one line to the other (one node to the other) makes half a wavelength
which is 6cm
one full wavelength is thereofre 12cm so its D


Q31
first find total resistance :
(6*3)/(6+3)=2
2+2= 4 ohms
total R= 4 ohms
total V=12V
now find voltage for the parallel connections , treat the 6ohms and 3ohms as a single resistor so:
(6*3)/(6+3)=2
2* current = 2*3=6V
since its parallel , the 6ohms gets 6V so does the 3ohms
so
R=V/I
I=V/R
I=6/6= 1 A

got it?

[astarmathsandphysics]

If noone answers am home in 90 mins

[ruby92]

M/j 2004 9 14 (why isnt it A)
31 (why not C) 21 20

[halosh92]

M/j 2004 9 14 (why isnt it A)
31 (why not C) 21 20

Q14: its B because its in equiliberium which means the triangle arrows must be head to tail like in B
Q31: R=V/I
R=row L/A
since V , L ,row are same they cancel out so we can write it like this
1/I = 1/A  (THIS IS FOR P)=1/A(THIS IS FOR Q)

FOR P:
A= pie r^2  thereofre
1/pie

FOR Q:
A=pie r^2 therefore
1/pie 4
 
we cancel out the pie this remains
P:Q
1:1/4
so P is 4 times bigger than Q so its D

20: D (brownian motion)