Physics: Post your doubts here!

[ashcull14]

Q2 P22 june 2012

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_13.pdf

q24

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_11.pdf

q23

24 you are given the spring constant the firmula for spring constant is K=F/e
where K is the spring constant F is the force and e is the extension
as the trolley is that rest the force applied by P = force by Q
Force by P=k*e=60*0.40=24
Force by Q=k*e=120*e=24
e=24/120=0.2

 

[sadiaali]

Please someone tell how to calculate the percentage uncertainty.
Eg Measuring from vernier caliper, my reading is 3.52. How we will calculate the % uncertainty?

 

[Hijab]

Can anyone explain me this question???? I would really be grateful....

 

[FLRNAB]

Can anyone explain me this question???? I would really be grateful....

Do you know the correct answer?

It should be B.

On model all lengths are one tenth. So if there is extension of 1 m on real crane there would be a extension of 0.1 m on the model because 1/10 = 0.1

Dividing 1 by 0.1 results in 10 which is the same as 10 raised to power 1.

Just a guess.

 

[mehria]

thanks wat abt question 2 d ii)?

even m cnfused in it... :/

 

[usama321]

igot the same calculated results bt how did u conclude tht its b ..cn u explain fully plx?

The calculation shows that it takes 2 ms for one wave to complete its cycle. Now each square on the horizontal axis respresents 0.5ms. Thus dividing 2/0.5, it must take 4 complete squares for the wave to complete on cycle. That happens only in B

 

[Thought blocker]

The calculation shows that it takes 2 ms for one wave to complete its cycle. Now each square on the horizontal axis respresents 0.5ms. Thus dividing 2/0.5, it must take 4 complete squares for the wave to complete on cycle. That happens only in B

ashcull14

 

[Snow Angel]

lol

even m cnfused in it... :/

 

[talha-_-khan]

THIS IS THE 3rd TIME I AM POSTING THIS QUESTION SOME ONE PLZ ANSWER THIS QUESTION with explanation wont take more than 2 min

 

[usama321]

THIS IS THE 3rd TIME I AM POSTING THIS QUESTION SOME ONE PLZ ANSWER THIS QUESTION with explanation wont take more than 2 min

The piston is in equilibrium, as it is not moving. Thus outside pressure must equal the pressure inside. Thus force on piston
100000 * .003= 300N

Now, the area of the cylinder doubles, which halves the pressure inside it. Thus, the force on the piston now would be

50000* .003 = 150N

The reason i was not replying to your question was because i was confused about how the piston would remain in its place in diagram 2 as the air pressure outside is now more than the pressure inside. However, i had not read the question carefully enough as it said "held at". Sorry for the late reply

 

[usama321]

Can anyone explain me this question???? I would really be grateful....

Is the answer C?
Note: I am not complete sure about this question
extension = F * l/A*young modulus

Now in the model, all the linear dimensions are one tenth.

Now, the length, width and height of the load are 10 times the one in the model. Thus 10*10*10 = 1000 times the volume of the load in the figure. As volume and mass are directly proportional, the mass should also increase 1000 times, and so should the weight.

Now, the radius of the wire in the model is times the one in the model (linear dimensions) Thus the area should be 100 times more than the one in the model due to the square in the area of a wire

The length of the wire would just be more by a factor of 10.

The young modulus should not change, as it is the same for a material

(1000 * 10/100)/1 = 100

Kindly confirm about this one.

 

[Hijab]

Is the answer C?
Note: I am not complete sure about this question
extension = F * l/A*young modulus

Now in the model, all the linear dimensions are one tenth.

Now, the length, width and height of the load are 10 times the one in the model. Thus 10*10*10 = 1000 times the volume of the load in the figure. As volume and mass are directly proportional, the mass should also increase 1000 times, and so should the weight.

Now, the radius of the wire in the model is times the one in the model (linear dimensions) Thus the area should be 100 times more than the one in the model due to the square in the area of a wire

The length of the wire would just be more by a factor of 10.

The young modulus should not change, as it is the same for a material

(1000 * 10/100)/1 = 100

Kindly confirm about this one.

Yes the answer is C.... Thankyou very much...

 

[Hijab]

Do you know the correct answer?

It should be B.

On model all lengths are one tenth. So if there is extension of 1 m on real crane there would be a extension of 0.1 m on the model because 1/10 = 0.1

Dividing 1 by 0.1 results in 10 which is the same as 10 raised to power 1.

Just a guess.

The answer is C in the marki g scheme

 

[talha-_-khan]

The piston is in equilibrium, as it is not moving. Thus outside pressure must equal the pressure inside. Thus force on piston
100000 * .003= 300N

Now, the area of the cylinder doubles, which halves the pressure inside it. Thus, the force on the piston now would be

50000* .003 = 150N

The reason i was not replying to your question was because i was confused about how the piston would remain in its place in diagram 2 as the air pressure outside is now more than the pressure inside. However, i had not read the question carefully enough as it said "held at". Sorry for the late reply

Thanks

 

[Suchal Riaz]

Snow Angel

 

[Hijab]

If i am right, the circuit is like this
View attachment 39203


The current divides at A. Thus the two resistors from A to B and B to C are in series with each other, and the resistor connected diagonally is parallel with them. So,

1/r = 1/6 + 1/12
r = 4 ohm

Now after this, The next resistor between C and D is in series once again. Thus the resistance till here in the lower two loops become 4 + 6 = 10. Add it with the resistor in the upper loop

1/10 + 1/6
r = 3.75

The second part is correct.... The first part is wrong... As the answer is 3 ohms... But thankyou for ur help...

 

[usama321]

The second part is correct.... The first part is wrong... As the answer is 3 ohms... But thankyou for ur help...

Well, i only answered the second part For the first part, it would
1/12 + 1/6 + 1/12 = 3

 

[usama321]

The second part is correct.... The first part is wrong... As the answer is 3 ohms... But thankyou for ur help...

For the first part, the circuit is:
the upper two resistors are in series
The lower two resistors are in series
And the the one in the middle is well.. alone xD
And all the above are in parallel to each other
I made that diagram just for the second part, it is not applicable to part i

 

[biscuitbiscuit]

http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_w05_qp_2.pdf
"Q7 b(ii)1", why is it 2.7 when the volt metre says zero