Physics: Post your doubts here!

[nehaoscar]

It's C...
Why do you multiply by A for the upthrust??

 

[nehaoscar]

Why D?? How will it balance the force??

 

[nehaoscar]

How to do this??

 

[Kool boy]

Any idea about physics paper 32

 

[princess Anu]

y are we not considering the direction of velocity here? if I take -5 ans comes out to be C:/

 

[The Sarcastic Retard]

y are we not considering the direction of velocity here? if I take -5 ans comes out to be C:/

Square of negative quantity = positive quantity.
1/2 * 1000 * (25^2 - (-5)^2) = 300000 J

 

[funky brat]

Someone please explain ON 2011 paper 23 question 6 part c?

 

[funky brat]

View attachment 54111
How to do this??

Is that D?

 

[funky brat]

And also can someone please highlight that in MJ 2012 paper 23 question 5 part b i how do you get the current as 2 A?

 

[Ahmed Aqdam]

View attachment 54104
It's C...
Why do you multiply by A for the upthrust??

Pressure=Force/Area. Upthrust is a force so multiply by area to get force.

View attachment 54111
How to do this??

Power input= mgh/t
200*9.81*8=15696
Output=32*230
=7360
Efficiency=7360/15696*100
=47%

 

[The Sarcastic Retard]

Can somebody please explain this? View attachment 54097

Total spring constant (P,Q) = k + k = 2k Total spring constant (P,Q,R) = 1/2k + 1/3k = 5/6k Force |W| = kx x = |W|/k = 5W/6k

 

[The Sarcastic Retard]

And also can someone please highlight that in MJ 2012 paper 23 question 5 part b i how do you get the current as 2 A?

Already specified in question.
R = V/I - (r1+r2) = 8/2 - (0.5+0.1) = 3.4ohm.

 

[princess Anu]

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

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

 

[Boss201]

(June 2005/P22/Q5)

(b) light wavelength of 590nm is incident normally on a diffraction grating having 750 lines per millimetre.

the diffraction grating formula may be expressed in the form


(i) calculate the value of d , in metres , for this grating.(it gave no value for the angle theta ; how to proceed ? why ?)

(ii) determine the maximum value for the light incident normally on the grating.

Thanks

 

[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 :/