Physics: Post your doubts here!

[Rahma Abdelrahman]

Q. 29 the answer is c, because what causes the difference between pd and emf is always the internal resistance of the cell. B is wrong because it doesn't really make any sense, connecting wires have absolutely no effect on the emf of a cell.
Q.1 you have to arrange the momentum formula and ke formula to get ke=p2/2m,then substitute ke1 and ke2 and put them over each other, cancel p(momentum) then just solve the equation, the answer is A.
Q.2 I don't really understand the correct answer, but you're wrong because both points on the diagram are going in, meaning they are both negative, therefore they repel not attract.

Q1. I know we have to arrange it but i dont get how to do that.. how did u get ke=p2/2m?
Thanks

 

[bogus]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_11.pdf
question 36 ... syed1995 h4rriet . Thanks in advance guys!

 

[nodyed]

help pls! haha101

 

[nodyed]

this one too?

 

[nodyed]

explanation?

 

[Tkp]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_11.pdf
question 36 ... syed1995 h4rriet . Thanks in advance guys!

well c the voltmeter is connected with the fixed resistor
apply the formlua of potentiometer
p/p+q*emf(where p is the fixed resistor resistance and q is the variable resistor)
so increasing the q decreases the voltage so voltage decrases
and the ammmeter is directly connected with the fixed resistor so there is no change in readings.Hope it helped u

 

[Omar99]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s11_qp_11.pdf
this one please in question no. 13, 18, 19 and 27

 

[syed1995]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_11.pdf
question 36 ... syed1995 h4rriet . Thanks in advance guys!

Increasing the variable resistor's resistance will make more PD fall on the variable resistor and less resistance on the fixed resistor! so Voltmeter reading will decrease..

But The ammeter reading will stay unchanged.. since the voltage in parallel circuits is same.. so according to the formula V=IR .. if R remains same I will remain same too.

so Answer should be C.

 

[asangietalks]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w11_qp_12.pdf
no 31 can someone explain why the answer is A?

 

[abruzzi]

Someone please please help me understand the following questions:
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_w05_qp_1.pdf
Qn no. 28, 33, 34
syed1995

 

[Tkp]

hey help me in oct nov 09-28,21,13,12

 

[syed1995]

Someone please please help me understand the following questions:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w05_qp_1.pdf
Qn no. 28, 33, 34
syed1995

x=lambda*D/a
(Lambda/2*D)/2a
x=1/4*Lambda*D/a
so answer should be.. 0.75. A

33

Two Equations

1) R = pL/A
2) Strain = F/A

If strain increases area decreases... according to 2.

Then according to 1 .. If A decreases R increases. So answer is D.

34 ..

draw a line from origin to each of the points... whichever has the lease gradient will give you the answer.. since gradient of the graph is I/V .. and resistance is V/I.. so we need the least gradient. as resistance is 1/gradient so Answer is C

 

[syed1995]

hey help me in oct nov 09-28,21,13,12

Which Variant?

 

[Tkp]

Which Variant?

11

 

[abruzzi]

x=lambda*D/a
(Lambda/2*D)/2a
x=1/4*Lambda*D/a
so answer should be.. 0.75. A

33

Two Equations

1) R = pL/A
2) Strain = F/A

If strain increases area decreases... according to 2.

Then according to 1 .. If A decreases R increases. So answer is D.

34 ..

draw a line from origin to each of the points... whichever has the lease gradient will give you the answer.. since gradient of the graph is I/V .. and resistance is V/I.. so we need the least gradient. as resistance is 1/gradient so Answer is C

Thanks a lot brother
For no. 33, isnt it strain = extension/original length?

 

[syed1995]

Thanks a lot brother
For no. 33, isnt it strain = extension/original length?

Ah my bad.. you'd use

E=Stress/Strain
Strain*E=F/A
If strain increases then Area decreases.

 

[syed1995]

hey help me in oct nov 09-28,21,13,12

12B

R1=R2 is obvious since the force downwards will be same..

So force is R1=2*T1Cos(Theta) and R2=2*T2Cos(Theta) .. as R1=R2 .. As Theta is greater in 1 more force will be required. so T1>T2.

13 No Clue.

21 it's kinda logical.. If you draw a straight line from origin to P.. you will see that the strain energy coming as 0.10 J.. and will also see that there is some area above the line you drew as well.. so there will be more a little more energy than 0.1... so answer is C.

28 No Clue.

 

[tysler]

A particle of mass 2m and velocity v strikes a wall.
The particle rebounds along the same path after colliding with the wall. The collision is inelastic.
What is a possible change in the momentum of the ball during the collision?
A mv B 2mv C 3mv D 4mv

answer is C.. plz someone explain

The collision is inelastic so the speed of the ball after rebounding will be less than v but greater than 0. the answer cant be A or B because the change has to be greater than 2mv since it changes direction. d also cant be because it would make the collision elastic thus c as rebound speed is 0.5v which is in possible range

 

[haha101]

this one too?

B as one block is already in place n we have to stack thre more

 

[h4rriet]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_11.pdf
question 36 ... syed1995 h4rriet . Thanks in advance guys!

The reading on the voltmeter decreases because more voltage goes to the variable resistor. The reading on the ammeter isn't changed because the resistance of the resistor it is connected in series with is the same.