Physics: Post your doubts here!

[princess Anu]

^ I saw it there but it isn't specified there as to why do we have to use the diameter.

 

[Maayee]

could anyone explain me question no. 20 http://studyguide.pk/Past Papers/CIE/International A And AS Level/9702 - Physics/9702_s05_qp_1.pdf

 

[Ahmed Aqdam]

http://maxpapers.com/wp-content/uploads/2012/11/9702_s13_qp_11.pdf

Q17.. why is it imp to consider the diameter? :/

Height will be taken from the bottom as when the ball hits the surface its height will be zero.

 

[Ahmed Aqdam]

could anyone explain me question no. 20 http://studyguide.pk/Past Papers/CIE/International A And AS Level/9702 - Physics/9702_s05_qp_1.pdf

The extension provided by each spring is e.
X: Springs are in parallel so extension will be 1/e+1/e=1/(resultant extension). Hence resultant extension is e/2.
Y: For both the series combinations the extension is 2e. Considering the parallel combinations: 1/2e+1/2e=1/(resultant extension). Hence resultant extension is e.
Z: For parallel springs extension is e/2 and when added to the 3rd spring the total extension is 3e/2.
So order of increasing extension is X-Y-Z.

 

[nehaoscar]

Is that D?

Yes!

 

[princess Anu]

can somebody please explain why not C?
the pressure exerted by the gas in the flask on the right end of the tube causes the level to fall in it thereby causing the left hand tube level to rise, no?? :/ so the pressure exerted actually shud be only density*g*h because the reason why LEFT hand tube is rising is actually because the RIGHT hand tube level is falling, right? but this way the ans shud be C :/

 

[Furqan Azam]

for 33 see solution 387 at
http://physics-ref.blogspot.com/2015/02/physics-9702-doubts-help-page-71.html

How do you ask that blogger to solve some questions. I mean where to post the comments?

 

[asadalam]

Can someone explain these to me? Physicist

 

[asadalam]

Many of these have already been solved. Could you search in the specific paper at
http://physics-ref.blogspot.com/2014/05/physics-9702-notes-worked-solutions-for.html

I searched the blog for june 2003 but only two of these i found solved (35 and 10) rest i couldnt find :/ Any help?

 

[Ahmed Aqdam]

Can someone explain these to me? Physicist

View attachment 54164 View attachment 54165 View attachment 54166 View attachment 54167 View attachment 54168

20. Here
5. Here
22. There are three springs with extension x so the total extension due to weight W is 3x. The extension due to 2W will be 6x. When one spring is removed and two are left the extension on both due to 2W will be 3x.

Just a note on 35: This is probably the most repeated question ever. The trick here is to know that the d in the formula E=V/d is the separation of the plates and not the distance from the plates. The separation remains constant and so does the electric field.

 

[69ermalik007]

Plz help..... I cant solve this question

 

[princess Anu]

why is it D? :S :/

 

[princess Anu]

why is P < R ?

 

[princess Anu]

see 325 at
http://physics-ref.blogspot.com/2015/01/physics-9702-doubts-help-page-56.html

how do we know if the sphere is stationary or moving up/ down ? :/ may be its weight is greater than upthrust,who knows? how can we assume it to be moving upwards & conclude that R is greater than P :/

 

[Farhad221]

the answer is A can anyone explain with the calculation

 

[Farhad221]

And this one the answer is D

 

[Ahmed Aqdam]

the answer is A can anyone explain with the calculation

The extension provided by each spring is e.
X: Springs are in parallel so extension will be 1/e+1/e=1/(resultant extension). Hence resultant extension is e/2.
Y: For both the series combinations the extension is 2e. Considering the parallel combinations: 1/2e+1/2e=1/(resultant extension). Hence resultant extension is e.
Z: For parallel springs extension is e/2 and when added to the 3rd spring the total extension is 3e/2.
So order of increasing extension is X-Y-Z.

And this one the answer is D

According to Young Modulus formula: F=EAe/l, force is directly proportional to area and inversely proportional to length.
The tension in P is T.
Tension in Q will be halved due to the double length and will be halved further due to the half cross-sectional area. Hence it will be T/4.
(T)/(T/4) is 4 or 4/1.

 

[Ahmed Aqdam]

Help needed

The weight of one person is 588.6 N so weight of 20 people will be 11772 N.
The force in the direction of motion is 11772*30/60=5886 N.
Multiply this by 0.75 to get the power which is needed to drive the passengers.
Add 2.0 kW as it's the power to drive an empty escalator.

 

[69ermalik007]

Need desperate help.....

 

[69ermalik007]

and in these..........