Physics: Post your doubts here!

[MEGUSTA_xD]

another question when we make a solution of two miscible liquids the boling point of the solution is effected...now ignore that whether it increases or decreases but the whole sol. has a uniform boiling point...if it is so then how we will perform the process of fractional distillation????

Chemistry question, i believe this is a application question, it's about successive extraction, pg 82. In chem app booklet.
They might have same bp, but not solubility in certain solvent.

 

[leadingguy]

a beam of monochromatic lite of wavelengh 630nm trnsports energy at the rate of 0.25mW. calculate the no. of photons passing a given cross section of beam each second.(planck cnstant=6.6*10-34,speed of light=3.0*108)

ans is [8.0*1014] ..................*10 stands for exp

 

[leadingguy]

View attachment 4862

did u find ur ans?? is it really option D???? let me know abt it??

 

[Duanoor]

Chemistry question, i believe this is a application question, it's about successive extraction, pg 82. In chem app booklet.
They might have same bp, but not solubility in certain solvent.

i did o lvls and thn doing fsc and dnt have tht book...cn u pls upload tht page...​

 

[maybeitwasnoone]

a beam of monochromatic lite of wavelengh 630nm trnsports energy at the rate of 0.25mW. calculate the no. of photons passing a given cross section of beam each second.(planck cnstant=6.6*10-34,speed of light=3.0*108)

ans is [8.0*1014] ..................*10 stands for exp

Use E=(hc)/lambda. where E=(6.63*10^-34*3*10^8)/(630*10^-9) E=3.157*10^-19 J is the energy of one photon.

You have the beam transporting energy at the rate of 0.25mW=0.25mJ So Divide 0.25*10^-3 by 3.157*10^-10 to obtain the number of photons. You get 7.92*10^14 photons being transported.

 

[Silent Hunter]

Total work done= Work done against friction+Work done to increase the Potential Energy
=150*1.5/sin30+200*1.5
=450+300
=750J (D)

Can you please explain the highlighted part? Thank You

 

[Silent Hunter]

did u find ur ans?? is it really option D???? let me know abt it??

yes....option D.

 

[MEGUSTA_xD]

i did o lvls and thn doing fsc and dnt have tht book...cn u pls upload tht page...​

http://www.xtremepapers.com/community/attachments/9701_chemistry_applications_booklet-pdf.3845/ here you go

 

[leosco1995]

November 2010, P11, Q24.

How is the answer A?

 

[abcde]

November 2010, P11, Q24.

How is the answer A?

I'm using x to denote the intensity of the emerging light.
I/x = a^2/(a cos 60*)^2
=> 1/x = a^2/ 0.25 a^2
So, x = 0.250 I.

 

[abcde]

Can you please explain the highlighted part? Thank You

Highlighted part: work done against friction = frictional force x distance moved due to friction (which is up the slope).
Use trigonometry to find that distance. It's 150/sin 30*.

 

[leosco1995]

Oh, I made a pretty stupid mistake. Thanks.

 

[Duanoor]

http://www.xtremepapers.com/community/attachments/9701_chemistry_applications_booklet-pdf.3845/ here you go

thnx

 

[Oliveme]

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

 

[omg]

http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_w07_qp_4.pdf
can smbody explain q7 part c to me please!!

 

[Albert Einstein]

http://www.xtremepapers.com/community/threads/physics-problem-urgent-help-plzzzzz.12508/

 

[hassam]

http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_w07_qp_4.pdf
can smbody explain q7 part c to me please!!

see Kr has half life of 3 s.....there are two ways....one that u can set up an equation but thats more error prone so better off stick with the second method.........that after 1st 3 s Kr wd be 1/2.....after another 3 s it wud be 1/4th ......and after another 3 it wud be 1/8th whereas because of comparatively very big half life of Ba.....it wud decay be very small amount so after approx. 9 sec rattio will become 8
@OMG i Wanted to ask about an upper part of this question that why is fission energetically feasible......so ms was saying greater binding energy of products compared with reactants....bt how does it explain the energitcally feasible thing

 

[hassam]

how will i determine the frequency of unmodulated carrier wave

 

[Oliveme]

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?

 

[rz123]

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?

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