Physics: Post your doubts here!

[anahita16]

Can someone explain how we got the answer to number 37 in this paper: http://www.xtremepapers.com/CIE/Interna ... _qp_11.pdf

November 2010 paper 11

http://www.doctronics.co.uk/voltage.htm

V= R/(R+r) * Vin

 

[KaiserFury]

Yes, I know that, but why is the correct graph the one where voltage is constant?

 

[rz123]

^it should be B.resistance is decreasing so output voltage should also decrease with it i think. maybe the ms is wrong

or maybe the voltmeter is connected across the end terminals completing the circuit whereas it shud be against P only to get its output voltage, so here no matter wherever u move the slider the voltmeter will record the e.m.f of battery being 4 volt. i m not sure

 

[XPFMember]

Assalam-o-alaikum!


Can somebody explain Q:9 (b) of June:2009 Paper:4

Jazak Allah Khairen!

 

[jihan911]

plz help!!this problem is really hard Q:29 of M/J 09 paper 1..

 

[markskoop]

here final velocity = 0
inital velocity = v
e-field = E
so
or, f = eE
or, ma= eE
or a = eE\m------1)
now
v^2 = u^2 + 2as
since its abt to stop so its deceleration
0 = v^2-2ax
v^2= 2 * eE\m *x
so x= (v^2 * m)\(2eE)
so answer is D

 

[markskoop]

need help with this one

 

[XPFMember]

Assalamoalaikum!

Check this post!

 

[SHUBHAsnlnm]

physics paper 1 help

http://www.xtremepapers.com/CIE/Interna ... 2_qp_1.pdf
question number 35. explanation please

 

[rz123]

i think it's A as resistance of the circuit increases so P.d will also increase with it (directly proportional). the needle will deflect towards X as current flows from - to + so it will deflect in this direction.

 

[XPFMember]

Assalam-o-alaikum!


Can somebody explain Q:9 (b) of June:2009 Paper:4

Jazak Allah Khairen!


& I also am confused abt a sentence in the book...under features of stationary waves:

The amplitude of vibration varies with position along the string: it is zero at node, and maximum at antinode. In a progressive wave, all points have same amplitude.

Can someone plz explain this...how same amplitude in progressive? and also when we have to show the antinodes...how are we supposed to show them? as a single point at the top or...a line from top to bottom?

 

[OakMoon!]

It is a very basic decay question but they have just confused you with the "calibration" and "uncertainty" words. You'll take the negative errors on both values to show DECAY. Solve the rest of the question in the following way using the decay equations.



You use a dot to represent the antinode. You can show it either on the top, or at the bottom or at both sides. Progressive waves are formed due to the movement of particles perpendicular to the direction of wave. Each particle vibrates with the same amplitude. Though, the formation of sinosuidal wave takes place because at a certain time not all particles are at their amplitude and have different displacements.

 

[tanmaydube]

A rubber rope of mass m and length x is stretched by a tension force T.
When the rope is moved up and down a wave moves along the rope with a velocity v.
Which equation is homogeneous and thus could be correct?

A v2=Tmx−1
B v2=Tm−1x−1
C v2=Tm−1x
D v2=Tmx

Please explain thank you!

 

[abcde]

A rubber rope of mass m and length x is stretched by a tension force T.
When the rope is moved up and down a wave moves along the rope with a velocity v.
Which equation is homogeneous and thus could be correct?

A v2=Tmx−1
B v2=Tm−1x−1
C v2=Tm−1x
D v2=Tmx

Please explain thank you!

C ! Express each physical quantity in terms of its base quantities and then compare the right and left hand sides of each equation. Only C gives R.H.S. = L.H.S.
as shown: LHS= v^2 = (ms^-1)^2 = m^2 s^-2
RHS = T(m^-1)x = kg m s^-2 kg^-1 m = m^2 s^-2.

 

[rz123]

any questions missed previously or you got some now of As level physics? post them !
i will try to help with the best of my ability!

 

[no.mercy]

1) I am stuck on how to find the direction of the resultant..can someone please guide me ..the answer given in the booklet is R is at an angle 112 to the 4 N vector. (90+22)
The screenie for the question is here..and the second is the way the question in the booklet has been done..i am not able to understand their method can someone explain pls

 

[abcd888]

ans to m/j 2004 q 1

can someone explain the vector question from may/jume 2004 Q1.
you have to find the resultant force, and the angle given is 40 with 8N and 6N forces.
answer is 13.2 N but how did it come?

 

[abcd888]

I AM STUCK IN FINDING THE RESULTANT IN PAPER MAY/JUNE 2004 q1. THE ANGLE GIVEN IS 40 WITH FORCES 6N AND 8N. WHAT WILL B THE RESULTANT FORCE AFTER DRAWINF VECTOR DIAGRAM. THE ANS IS 13.2 BUT HOW DOES IT COME?
only this is drawn

 

[Nibz]

Here's the solution:

 

[Dayyanah]

any one pls help!
show how simple pendulum exerts simple harmonic motion
thnx