Physics: Post your doubts here!

[Yousif Mukkhtar]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_11.pdf

please explain Q32,23,20.
I will be very thankful

Q32:
Resultant force is zero as forces acting on Q and -Q are same in magnitude but opposite in directions. Now you can see that both forces form a couple which turns the rod anticlockwise.

Q23:
Both wires are of the same material which is steel so both Young modulus are exactly same. DImensions do not matter when materials are exactly same
Q20:
Formula for PE is mgh

Here E is the potential energy lost. So:
pe=mgh
E=mgx
g=E/mx and this happens in the right direction. If it is in the opposite direction pe is gained not lost!

 

[A*(a*)]

Thank you! This is really helping me practice. I'm sure you'll nail an A*!

thanks do pray for me, I just need your prayers

 

[Zsiddiqui]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_12.pdf please help in question numbers : 15, 25,26 and 33. Thanks in advance

 

[A*(a*)]

Haha this for A2 but it is easy just get mgh and divide by its respective masses and there bingo

is it sth. related to A2? oh so i do not need to do it, han?

 

[Rahma Abdelrahman]

June 2012 P12 Q18..
Can anyone solve this?

 

[Warrior66]

You helped me alot. Thank you for the great help and may Allah shine you with all As this May june session

Jazaka'Allahum Khairan! A'ameen, and I pray the same and more for you!

 

[TaffsAsLevel]

Tougher than CIE?

Oh yess, I think CIE is the easiest branch of Alevels, they don't have those additional chapters like optics,astronomy etc. They also have more depth in details per chapters

 

[TaffsAsLevel]

is it sth. related to A2? oh so i do not need to do it, han?

gravitational potential or phi is in gravitation chapter in A2 but in here it is for you because they gave you the unit, Jperkg (part of physical quantities) so we just divide it by its mass to get the magnitude

 

[TaffsAsLevel]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_11.pdf

please explain Q32,23,20.
I will be very thankful

for 32, resultant force is zero because it rotates at a constant speed because and anti clockwise because E is downward so downward is negative so it repels it and it became anti clockwise, C

For 23, try to compare both of the E for their respective length and radius then compare the multiples, I can't do the working its too long, answer B

For 20, E=mgx so g is the accelration due to gravity therefore g=E/mx or magnitude=E/mx and direction is toward earth but it says loses EPE so direction must be towards the right isn't it because it says P to Q. so A

 

[h4rriet]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_12.pdf please help in question numbers : 15, 25,26 and 33. Thanks in advance

15. mg-kv=o because the velocity is constant so the resultant force = o. Make v the subject and use 1/2m(v^2) to find the K.E.
25. The fundamental frequency in tube X will be when lambda = 1/4, and in tube Y when lambda = 1/2.
26. v=fxlambda. Find the wavelength (it's twice the distance between two adjacent nodes).
33. Do this using E=I(r+R). If E doesn't = I(r+R), then you'll know that that combination is wrong.

 

[h4rriet]

June 2012 P12 Q18..
Can anyone solve this?

12. The relative velocities of approach are u1--u2=u1+u2. The relative velocities of separation are v1+v2.
18. (32 x 230)/(200 x 9.81 x 8).

 

[Zsiddiqui]

15. mg-kv=o because the velocity is constant so the resultant force = o. Make v the subject and use 1/2m(v^2) to find the K.E.
25. The fundamental frequency in tube X will be when lambda = 1/4, and in tube Y when lambda = 1/2.
26. v=fxlambda. Find the wavelength (it's twice the distance between two adjacent nodes).
33. Do this using E=I(r+R). If E doesn't = I(r+R), then you'll know that that combination is wrong.

thank you so much

 

[abdullahaftab]

Light of wavelength 700 nm is incident on a pair of slits, forming fringes 3.0 mm apart on a screen.
What is the fringe spacing when light of wavelength 350 nm is used and the slit separation is
doubled?
A 0.75 mm B 1.5 mm C 3.0 mm D 6.0 mm

Any idea How to solve this ???

 

[talalz]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s12_qp_11.pdf

its summer/11/2012... can any one explain mcq no, 4,8,12,15 .. please

thank you​

 

[ahmed abdulla]

12. The relative velocities of approach are u1--u2=u1+u2. The relative velocities of separation are v1+v2.
18. (32 x 230)/(200 x 9.81 x 8).

Q1 A box of mass 8.0 kg rests on a horizontal, rough surface. A string attached to the box passes
over a smooth pulley and supports a 2.0 kg mass at its other end.
When the box is released, a friction force of 6.0 N acts on it.
What is the acceleration of the box?
answer is 1.4ms-2
can u solve it via newton second law plz?

Q2--

An electric power cable consists of six copper wires c surrounding a steel core s
1.0 km of one of the copper wires has a resistance of 10 Ω and 1.0 km of the steel core has a
resistance of 100 Ω.
What is the approximate resistance of a 1.0 km length of the power cable?
B 1.6 Ω

 

[ShaanSiddiq090909]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w09_qp_11.pdf
Question no 4

 

[a.abid]

http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s07_qp_1.pdf
Can anyone please explain q.3, 10, 11, 12, 20, 37

 

[Rahma Abdelrahman]

12. The relative velocities of approach are u1--u2=u1+u2. The relative velocities of separation are v1+v2.
18. (32 x 230)/(200 x 9.81 x 8).

I actually said P12 not Q12.. thnx anyways! But, for Q18, isnt the 230*32 the input energy?

 

[a.abid]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_11.pdf
Question no 4

The answer is C, right?

 

[ShaanSiddiq090909]

The answer is C, right?

Nope. It's A!