Physics: Post your doubts here!

[ZaqZainab]

which paper was it ?

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w09_qp_21.pdf

 

[Thought blocker]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_21.pdf

Nah, I suck. Help me with 5c

 

[Jelleh Belleh]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_21.pdf

Use v^2 = u^2 + 2as
(1.7x10^7)^2 = 0 + 2 (a) (4.5/100)
a = 3.2x10^15 m/s^2

 

[ZaqZainab]

Use v^2 = u^2 + 2as
(1.7x10^7)^2 = 0 + 2 (a) (4.5/100)
a = 3.2x10^15 m/s^2

Thanks
here is what i did i found the time using Speed=distance/time
and then used the equation Acceleration=(v-u)/t what is wrong with this?

 

[ZaqZainab]

Nah, I suck. Help me with 5c

Show diffraction of light
and double slit experiment

 

[Thought blocker]

Show diffraction of light
and double slit experiment

ok

 

[ShreeyaBeatz]

Finally I got all of the answers of the paper Paper was easy, here you go, hope this is correct... resistance is zero so pwer is zero obvious and in infinite resistance no current passes so zero rsistance i guess...

By P=( V^2/ R)
if R is zero, how is V zero? It should be infinity right?

 

[Thought blocker]

By P=( V^2/ R)
if R is zero, how is V zero? It should be infinity right?

PLEASE EXPLAIN HER, I AM BUSY YOU KNOW
Suchal Riaz

 

[M.Shahzaib Shoaib]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w09_qp_22.pdf


Question 3 C(ii) : Why do you add the velocities while calculating momentum ?


Question 4 C ii(3) : Why do we subtract g.p.e & e.p.e to get Work done ?


Question 5 (b) ?? : How is the phase difference 180 degrees ?

 

[Suchal Riaz]

By P=( V^2/ R)
if R is zero, how is V zero? It should be infinity right?

Look, these equations are not used to define any of these quantities. like V=IR or P=w/t.
Basic concept:

-no power will be dissipated by the resistor if it's resistance is zero.
reason:

V=energy/charge. If R is zero then V is zero it means that it uses no energy for each columb of charge that passes through it. If it uses no energy it means it's power is zero.​

Why your argument is wrong(but equation is not wrong):

p=V²/R
R is zero power is infinity? no if R is zero then V is also zero. But zero / zero is not defined. so this equation is not defined for V or R zero or infinity. the actual equations says "power is directly proportional to square of V and inversely proportional to resistance for resistance and voltage are not equal to zero" there is a restriction to every equation. like sine of an angle can't be bigger than 1. this is restriction of sine inverse function.​

 

[Suchal Riaz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_22.pdf


Question 3 C(ii) : Why do you add the velocities while calculating momentum ?


Question 4 C ii(3) : Why do we subtract g.p.e & e.p.e to get Work done ?


Question 5 (b) ?? : How is the phase difference 180 degrees ?

these two velocities are in opposite direction. so if one is positive other is negative. V1-V2. in this case V is vector velocity. lets say U is speed. U1-(-U2)=U1+U2
always treat vectors like vectors. they can't be added or subtracted like numbers. in two dimension always declare one direction positive so opposite to that direction is negative. 2 m/s is magnitude of velocity not velociy. +2 or -2 m/s is velocity becuase it tell us if it is in positive direction or negative.
Q4(c)(ii) because energy is conserved.
Q5 (b)
in one loop all points are in same phase. in adjacent loop they are in opposite phase. which means 180 degree. their ||displacement|| is same but in opposite direction.

 

[ZaqZainab]

Look, these equations are not used to define any of these quantities. like V=IR or P=w/t.
Basic concept:

-no power will be dissipated by the resistor if it's resistance is zero.
reason:

V=energy/charge. If R is zero then V is zero it means that it uses no energy for each columb of charge that passes through it. If it uses no energy it means it's power is zero.​

Why your argument is wrong(but equation is not wrong):

p=V²/R
R is zero power is infinity? no if R is zero then V is also zero. But zero / zero is not defined. so this equation is not defined for V or R zero or infinity. the actual equations says "power is directly proportional to square of V and inversely proportional to resistance for resistance and voltage are not equal to zero" there is a restriction to every equation. like sine of an angle can't be bigger than 1. this is restriction of sine inverse function.​

What about infinite resistance?
V=energy/charge. If R is INFINITE then V is Infinite it means that it uses infinite energy for each columb of charge that passes through it. If it uses infinte energy it means it's power is infinite. ??????

 

[Suchal Riaz]

What about infinite resistance?
V=energy/charge. If R is INFINITE then V is Infinite it means that it uses infinite energy for each columb of charge that passes through it. If it uses infinte energy it means it's power is infinite. ??????

sister there are few problem in what you said:
1 infinity is not a number
2 and you can say x=∞. correct way is x-->∞ which means it 'tends to infinity' so it never reaches infinity but it tends towards infinity.
3 in classical mechanics we use infinity to say very large compared to some thing. like we say S>>V means S is infinately bigger than V. like rest mass of proton compared to earth.

now we talk about equation. If R is infinite it means, by definition, that no current pass through it. a circuit which is not closed has infinite resistance. if that's the case then P=I²R so P---> 0*∞ which is not defined.

we say that no power is dissipated in volt meter because almost no current pass through it/has inifnite resistance. actually it has much more resistance then circuit but not truly infinite. like 3 Kilo Ohm voltmeter for circuit of combined resistance of 5 ohm.

 

[mohammad hurani]

help

 

[Zepudee]

how to do q(ii)?

 

[DeViL gURl B)]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w09_qp_22.pdf

Question 5(b) ? Guys how is it 18o degrees?
Plus in question 4 (c) (ii) please explains, the entire part!
Thank u!

 

[Talha Irfan]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_22.pdf

Question 5(b) ? Guys how is it 18o degrees?
Plus in question 4 (c) (ii) please explains, the entire part!
Thank u!

Phase Diff. Query : Firstly, we need to know that these both points are out of phase as they lie in alternate loops. Now if one point would have been on crest and the other on trough, you would have realized easily that their phase difference is 180. But what they did is they shifted the crest point to the left and the trough point to the right with same distance (as they both lie same distance from ends), so now again they would maintain the phase difference of 180 because they are equally distant apart as they were previously

 

[Talha Irfan]

help

eV is a symbol used in Nuclear Physics to denote the value of 1.6 * 10^-19
so if eV is the above mentioned value then, 8.5*10^-3 has 8.5*10^-3/ 1.6 * 10^-19 = 5.3125*10^16 eV
M denotes Mega which is the suffix of 10^6 so there are 5.3125*10^16 * 10^-6 (going from smaller unit to larger) = 5.3125 MeV = 5.3 MeV (shown)

 

[DeViL gURl B)]

Phase Diff. Query : Firstly, we need to know that these both points are out of phase as they lie in alternate loops. Now if one point would have been on crest and the other on trough, you would have realized easily that their phase difference is 180. But what they did is they shifted the crest point to the left and the trough point to the right with same distance (as they both lie same distance from ends), so now again they would maintain the phase difference of 180 because they are equally distant apart as they were previously

Ohhh okhay thank you SOO MUCH!

 

[DeViL gURl B)]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_22.pdf

Question 4 (ii) ? Please explain
Thank u