Physics: Post your doubts here!

[Charlotte20102013]

Can someone please help with this
http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s10_qp_11.pdf
Q33 (Ans: A) (Also, are all three P Q and R parallel to each other)?

 

[Thought blocker]

Can someone please help with this
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_11.pdf
Q33 (Ans: A)(Also, are all three P Q and R parallel to each other)?

There are lots of ways for this question
I find V the easiest to use in an explanation
PQR all have same resistance
Q,R have same V while P has 2x of their V so 2V
Power = (V²)/R
so Power ratio of P Q R =((2v)²)/R: (V²)/R : (V^R)/R or 4:1:1
total power is 12, divided to 6 parts so Power of R is 2W

 

[Keirad]

Can someone help me with this - http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s08_qp_1.pdf
Q 14
I know the answer is A but I did not understand how to get it. Can someone please explain.

 

[Thought blocker]

Can someone help me with this - http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s08_qp_1.pdf
Q 14
I know the answer is A but I did not understand how to get it. Can someone please explain.

moment = force x distance
clockwise moment = anticlockwise moment
W x a + F x h = W x 2a

 

[Keirad]

moment = force x distance
clockwise moment = anticlockwise moment
W x a + F x h = W x 2a

But where is the pivot

 

[Charlotte20102013]

There are lots of ways for this question
I find V the easiest to use in an explanation
PQR all have same resistance
Q,R have same V while P has 2x of their V so 2V
Power = (V²)/R
so Power ratio of P Q R =((2v)²)/R: (V²)/R : (V^R)/R or 4:1:1
total power is 12, divided to 6 parts so Power of R is 2W

So is P Q and R parallel to one another? I'm always having trouble deciding whether they are parallel or in series.. How to differentiate them?

 

[controlled.chaos]

1)
View attachment 49201
2) Brownian motion, the molecules of liquid collide with the molecules of the pollen grains.

Thank you so much for the answers. This helped me alot.

 

[manutd96]

help me with this please..

Light passes through a diffraction grating ruled at
1000 lines per cm and the same wavelength of
light also passes through two narrow slits 0.5
mm apart. Both situations produce intensity maxima
and minima on a screen.
Which statement about the separation of the maxima on the screen and the sharpness of the
maxima is correct?
A
The diffraction grating maxima are less widely spaced and are less sharp than the two-slit
maxima.
B
The diffraction grating maxima are less widely spaced and are sharper than the two-slit
maxima.
C
The diffraction grating maxima are more widely spaced and are less sharp than the two-slit
maxima.
D
The diffraction grating maxima are more widely spaced and are sharper than the two-slit
maxima.

i dont get what 'sharper' means and how to prove which is more widely spaced? thanks! ans is d.

 

[manutd96]

check qu 126 at
http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-23.html

ps: if you are the one who left a comment at the blog on this qu, plz do not include links to the papers. Only refer to the year, variant, qu no.
thanks

ok thanks.. i will do that from now on.. i hope u can help me with my latest question also thank you

 

[controlled.chaos]

Wslm.
view qu 114 at
http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-21.html
for the 1st question.
the other one will be added soon

Thank you so much for the help.

 

[Noman.Ahmed]

Solution please.. Ans is C

 

[Noman.Ahmed]

Explain. Ans B

 

[Noman.Ahmed]

Solution please

 

[Charlotte20102013]

Need help with some questions...
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s09_qp_1.pdf
Q7 (Ans: A)
Q13 (Ans: B)
Q18 (Ans: D)
TY!

 

[Charlotte20102013]

for q7, check solution 150 at
http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-26.html

check again there for the others

I can't find solutions for Q 13 and Q 18.

 

[Keirad]

Can someone please explain where the pivot is in my above question.

 

[Charlotte20102013]

But where is the pivot

You just have to take moments about a point. You can take it from any point on the ladder. In this case to get the answer you take it from the highest point of the ladder and apply the formula
clockwise moments = anticlockwise moments

 

[Keirad]

Can someone also explain Q 33 of May june 2006 P1

 

[Keirad]

You just have to take moments about a point. You can take it from any point on the ladder. In this case to get the answer you take it from the highest point of the ladder and apply the formula
clockwise moments = anticlockwise moments

Thank you

 

[Charlotte20102013]

Need help...
A ball is falling at terminal speed in still air. The forces acting on the ball are upthrust, viscous
drag and weight.
What is the order of increasing magnitude of these three forces?
A upthrust → viscous drag → weight
B viscous drag → upthrust → weight
C viscous drag → weight → upthrust
D weight → upthrust → viscous drag

Answer is A. But why?
Thank you !