Physics: Post your doubts here!

[unique840]

http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_s09_qp_4.pdf

http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_s09_qp_4.pdf qs.9 part (b)

the activity A0 is stated with 2% error. we hav to get the time for 10% ka error. means original se 8% error. if original is A0, then after 8% error, it will be 0.92A0. we will consider the expression: A = A0* e^(-lambda*time)
lambda will be 0.693/half life
lambda = 0.693/(5.27*365*24*3600)
A = 0.92 A0
so the equation will be:
0.92A0 = A0 * e^(-lambda*time)
A0 will be cancelled
0.92 = e^ (-lambda*time)
ln (0.92) = -lambda*time

 

[unique840]

Asalam-o-alaikum
Can you please help with these physics paper 1 questions?
Questions 13, 14, 16, 25, and 33. Thank you very very much.
http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_s05_qp_1.pdf

Please help me with these?

13) moments = force*perpendicular distance
5N and 10N force have anticlockwise moments. (5*2) + (10*2) = 30 N
20N force is clockwise. (20*3) = 60N
resultant = 60 - 30
= 30N

 

[unique840]

Asalam-o-alaikum
Can you please help with these physics paper 1 questions?
Questions 13, 14, 16, 25, and 33. Thank you very very much.
http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_s05_qp_1.pdf

Please help me with these?

33) resistance = (resistivity*length)/area
volume is constant. volume = area*length
length is doubled but volume is constant so area must be half.
area = A/2
length = 2l
resistance = (resistivity * 2l) / (A/2)
= (4*resistivity*l) / A
=4R

 

[unique840]

Asalam-o-alaikum
Can you please help with these physics paper 1 questions?
Questions 13, 14, 16, 25, and 33. Thank you very very much.
http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_s05_qp_1.pdf

Please help me with these?

25) intensity = A^2
I = A^2
2I = (A')^2 A' is the new amplitude
replace I with A^2
2 (A^2) = (A')^2
taking square root on both sides
A' = A * square root of 2
ans is B

 

[omg]

the activity A0 is stated with 2% error. we hav to get the time for 10% ka error. means original se 8% error. if original is A0, then after 8% error, it will be 0.92A0. we will consider the expression: A = A0* e^(-lambda*time)
lambda will be 0.693/half life
lambda = 0.693/(5.27*365*24*3600)
A = 0.92 A0
so the equation will be:
0.92A0 = A0 * e^(-lambda*time)
A0 will be cancelled
0.92 = e^ (-lambda*time)
ln (0.92) = -lambda*time

how did v get o.92Ao??

 

[leadingguy]

and i wanted to ask is there any site or sth were i can get the experiment design qs for p5, solved!??

no idont think that therres any site from which u can solved papers p5 apart p5 could only be tackled by practice as itx all abt calculations, measurements readings, callibiraations etc. u need a lot of practice and mark sceeme could assist u as solved ones.

 

[rz123]

13) moments = force*perpendicular distance
5N and 10N force have anticlockwise moments. (5*2) + (10*2) = 30 N
20N force is clockwise. (20*3) = 60N
resultant = 60 - 30
= 30N

can u plz tell me how does the 10 N force has an anticlockwise moment?

 

[leadingguy]

Re: Physics questions? please?

Question 10 Please.

Thanks!

well itx a big question what should I annswer to it??? u can get all the ans from marks scheme. apart if theres is any confusion in understanding any part of the question let me now abt it! what is that u are unable to understand ?? as if only ans is required than u can get it by mark scheme too????

 

[Mustehssun Iqbal]

Asalam-o-alaikum
Can you please help with these physics paper 1 questions?
Questions 13, 14, 16, 25, and 33. Thank you very very much.
http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_s05_qp_1.pdf

Walikum,
I haven't studied the whole course yet, and I can just coordinate with you on Q.14 and 16 for now.
Q.14
You take the "perpendicular" distance from the line of force to the pivot.
The 10 N force produces an anticlockwise moment. The 5N force also produces the same anticlockwise moment and the 20N force produces a clockwise moment about the pivot , P (see diagram).
You can take anticlockwise, or clockwise direction as positive and the other as negative. In this case, let us consider the anticlockwise moment as the positive direction for this question;
Torque = F1.d1 + F2.d2 - F3.d3
Torque = 10(2) + 5(2)-20(3)
Torque=-30N , i.e Torque=30N in the clockwise direction. Ans A
Q.16) P=W/t (Power=work done/Time taken)
m=(y2-y1)/(x2-x1)
m=40-10/3-2
P=30/1
P=30N Ans C
Also edited: The dotted lines in the diagram of Q.14 represent the perpendicular distances from the lines of forces to the pivot , P.

 

[omg]

can smby explain me the derivation of PV=NkT????

 

[leadingguy]

june o9

question 8 prt b please!
jxt let me know that what is being asked in the question. Am unable to pick up the meanings!

 

[unique840]

how did v get o.92Ao??

we have to find time for total error of 10%. it already has an error of 2%. means we have to find the time having an error of further 8%. the value given is Ao. 2% error is included in it. further error of 8% means Ao - 8% = 0.92Ao

 

[Oliveme]

14 D as the resultant together with other forces should originate from the same point. it should be springing outwards n upward direction. we can't show dat on a ppr so D looks appropriate in this case i guess.

16: the gradient will show us the power so the graph looks steepest from 2 till 3 seconds. the rise during this time is 30 joules and the time is 1 second so P= W.d / Time = 30W

Thank you

 

[unique840]

can u plz tell me how does the 10 N force has an anticlockwise moment?

if u apply the 10 N force on the lever, it will move upwards as it is pivoted at point P. therefore it is anticlockwise.

 

[unique840]

can smby explain me the derivation of PV=NkT????

PV = nRT
n is the number of moles. R is the molar gas constant
number of moles * avogadro constant(avg) = number of particles(N)
n = N/avogadro constant
k = R/avogadro constant
R= avogadro constant * k
PV = (N/avg) * (avg*k) * T
avg cancels out therefore
PV = NkT

 

[Oliveme]

33) resistance = (resistivity*length)/area
volume is constant. volume = area*length
length is doubled but volume is constant so area must be half.
area = A/2
length = 2l
resistance = (resistivity * 2l) / (A/2)
= (4*resistivity*l) / A
=4R

Thank you very much. God bless you.

 

[Oliveme]

25) intensity = A^2
I = A^2
2I = (A')^2 A' is the new amplitude
replace I with A^2
2 (A^2) = (A')^2
taking square root on both sides
A' = A * square root of 2
ans is B

Thank you so very much.

I've got more questions please? Physics paper 1 may 2011 questions 14, 15. thank you.

 

[unique840]

Thank you very much. God bless you.

ur welcum

 

[unique840]

june o9

question 8 prt b please!
jxt let me know that what is being asked in the question. Am unable to pick up the meanings!

p2 or p4?

 

[leadingguy]

p2 or p4?

p4