Physics: Post your doubts here!

[GarryTheGhost]

the answer is 20J. but how??????

 

[GarryTheGhost]

http://papers.gceguide.com/A Levels/Physics (9702)/9702_w16_qp_13.pdf
Q16,13 ,29,24,25 ANYONE
GarryTheGhost Thankyouuu!!

 

[SohaibButt]

Anyone?

 

[amina1300]

For those of you who couldn't solve this question :
Solution;
P=10^5-p(average)gh [ Basically you take the average density]

Question 15 Candidates found this question difficult. Atmospheric pressure is caused by the weight of air above the point, so the correct method is to calculate the pressure caused by the part of the atmosphere between sea level and 5000m, and to subtract this from the pressure at sea level. Candidates answering B or C had both calculated the pressure difference correctly using the average density; those choosing C gave the correct answer because they had subtracted the pressure difference from 100000Pa.

 

[Shimmery woods]

Anyone?

 

[SohaibButt]

Thanks a lot

 

[Shimmery woods]

que 30 anyone ??+

 

[selrey]

que 30 anyone ??+

Ans?

 

[Holmes]

Ammeter reading = 0
P.D across junction = 0
P.D(R4) = P.D(R2 )
R4/(R3 + R4) * V = R2 /( R2 + R1 ) *V
(R2 + R1)* R4 = R2 *(R3 + R4)
R2R4 +R4R1 = R2R3 + R4R2
R4R1 = R2R3

AND = D

oh finally got the answer
Thanks a lot.

 

[Holmes]

View attachment 62402

thnx

 

[Shimmery woods]

B

Ans?

B

 

[Holmes]

I guess you did it like this 8= ;[ 1/R + 1/2R ]^-1
2R/3 = 8
and R = 12

Thankyou the help.

you'r welcome anytime :

 

[Holmes]

E = (F/A) /( extension /length)
--> Stress : F/A
F = W = mg ( g is constant)
m = density * volume (density is constant as same material )
V = l * l* l ( The Load is a cube )
[The model is one tenth full-size in all linear dimensions.]
V = 1/10*1/10*1/10
V = 1/1000
When V decreases mass decreases and hence Force decreases
F = 1/1000
Area = A = l*l
= 1/10 * 1/10
= 1/100
So Stress = F/A = (1/1000)/(1/100) ---->1/10

----> Strain : e/l
Suppose extension = 1
length = 1/10
Strain = 10

E = stress/ strain = 0.1 / (10)
=> 1/100

Ration of original to model = 1/(1/100)
= 10^2 ANSWER = C

Great
no one could make me understand this question, but now I Got it.
Thanks again

 

[Holmes]

View attachment 62388
M/J 2016 (13)
Explain please

ANYONE ??????

 

[Holmes]

vertical:
v=u+at
v=8+(-1.62)(9)
v=-6.6ms-1
horizontal:
v=4ms-1
Resultant Velocity:
Sqroot of 4^2+6.6^2 = 7.7ms-1

thanks a lot .
I got it

 

[Holmes]

Ans is A
9702_13 2016

E = V/ d
V = E d
= 60000* (4/1000)
= 240 V

the confusion is that how the answer is -320V
Have a look

Q : Which potential should be applied to the upper plate to create an electric field of strength
60 000 V m–1 upwards in the space between the plates?

this means that
Electric field arrows go from -80V to the upper plate.
so we will do it like;
V = -80 -240
:. V = -320 v
I hope I make sense.

 

[selrey]

B


B

You'll take the distance between XY = 1/2 wavelenght. Then find frequency and the time period afterwards. You'll get T=1ms which is two 2 grids on the CRO

 

[student4563543]

the answer is 20J. but how??????

Initial kinetic energy of trolley = 4J

Consider the 1st case.
We need to consider the initial 4J here.
Final kinetic energy = 8J
Work done by force F (= Fs) = 8 – 4 = 4J
So, Fs = 4J

Consider the 2nd case.
Work done by force 2F = (2F) (2s) = 4(Fs) = 4(4) = 16J since Fs = 4J

Total kinetic energy = 4 + 16 = 20J

 

[student4563543]

E = V/ d
V = E d
= 60000* (4/1000)
= 240 V

the confusion is that how the answer is -320V
Have a look

Q : Which potential should be applied to the upper plate to create an electric field of strength
60 000 V m–1 upwards in the space between the plates?

this means that
Electric field arrows go from -80V to the upper plate.
so we will do it like;
V = -80 -240
:. V = -320 v
I hope I make sense.

thanks alot man

 

[Shimmery woods]

You'll take the distance between XY = 1/2 wavelenght. Then find frequency and the time period afterwards. You'll get T=1ms which is two 2 grids on the CRO

thankyou so much but the answer is B not D so i should be getting 4 grids
c =f* lamda
330÷ 66×10^-2
500 hz = 2×10^-3 S
2 ms = which will occupy 4 boxes on the Cro
THANKYOU SO MUCH I did a silly mistake of not considering half the wavelenght..