Post all of ur doubts here Mishi :)

[Mashal zeb]

According to syllabus, we must know that a proton has a charge +e (the basic/elementary charge)

Now according to this question, protons themselves are made up of particles called quarks. There are different types of quarks, each one with its own charge.

Whatever the combination of quarks, the total charge on a proton must be +e. Hence the sum of the charges of all the constituent quarks in a proton must be + e.

So simply check the sum of charges of each option to see if it is +e.

option A: 3 x (-e/3) = -e
option B: (2e/3) + (-e/3) = +(e/3)
option C: (2e/3) + 2(-e/3) = o
option D: 2(2e/3) + (-e/3) = +(3e/3) = +e

answer is D

I got it now thank u soo much

 

[Mashal zeb]

13)
5*2 is upwards and so is 10*2
while 20*3 is down wards
60-30=30 A

14)
View attachment 44728

Why 5 into 2? Which point have u taken as a pivot?

 

[Mashal zeb]

Q3

 

[Thought blocker]

Why 5 into 2? Which point have u taken as a pivot?

mehria help her, I need to run

Q3

Here we need to know estimates, I have attached a file, see there is answer of 4000J

gtg
All the best.

 

[mehria]

mehria help her, I need to run

Here we need to know estimates, I have attached a file, see there is answer of 4000J

gtg
All the best.

ok ok

 

[mehria]

Q3

As they r talkng abt an athlete so the best estimate of his speed will be 10m/s ...
n by putting ths in the equation:- mv^2/2 = 4000 = 4 x 10^3 J

 

[mehria]

Q13 nd 14

for 14:- first check for the resultant force of x n y component... i.e. 3 n 4...
the resultant force will be 5N
then we can see that 5 - 4= 1N so the resultant force will be in the direction shown in option D

 

[Mashal zeb]

Why wud it b in dat direction? Actualy m very confused abt vectors

 

[Kamihus]

Why wud it b in dat direction? Actualy m very confused abt vectors

The resultant of 3 and 4 will be between them so 4 will be opposite to it. 5 is greater than 4 by 1 so it will be in the direction of 5.

 

[mehria]

Q13 nd 14

 

[Mashal zeb]

Hadia i still did nt get ths one see point p is upwards wont we take 2 along wd other distancea becuZ da pivot z at p ryt?

 

[Asad rehman]

View attachment 44733

We have to take perpendicular distances to pivot from line of action so we are going in the way shown;
Sum of anti- clockwise moments =Sum of Clock wise moments
(5*2)+(10*2) = (20*3)
Resultant moments =60-30 =30Nm

 

[Mashal zeb]

How do we calculate tension?

 

[Thought blocker]

How do we calculate tension?

Use formula of young's modulus and make F as subject of formula, get for P and Q and then divide it

 

[Bilal Khan]

How do we calculate tension?

Young Modulus = Fl / Ae

 

[mehria]

How do we calculate tension?

ok so..
young modulus = Fl/Ae
be rearranging it we will get :- F= EAe / l
as they r made of the steel then their young modulus will be same so we will simply ignore it and the extension as well cuz we dnt have to do anything with it
we will assume that the value of A n l is 1
Fp = A/l = 1/1 = 1
Fq= (A/2) / 2l = 1/4

their ratio = 1 / (1/4) = 4

so the ans is D

 

[mehria]

Mashal zeb tmne to kaha tha k bht se problems hai... to sb post q nhi kr rhi bdtameez...?

 

[Thought blocker]

How do we calculate tension?