Physics: Post your doubts here!

[rideronthestorm]

 

[rideronthestorm]

 

[confused123]

plz explain all of these tooo View attachment 6426

right options in the marking scheme of all mcqz abv plz?

 

[rideronthestorm]

a,a,a,b,d,c in the order i uploaded

 

[hmlahori]

14 )View attachment 6425

wow you solved it.... that was really hard and it has a long solution..
physics paper 1 is genuinely hard!
well thanks.....

 

[Mustehssun Iqbal]

plz explain all of these tooo View attachment 6426

Love to answer this Physics question : )
You start with re-drawing or editting the diagram in the picture, and you mark the;
"perpendicular" distances from the lines of forces to the pivot and;
the motion of the rod in terms of whether it is deduced to be clockwise or anticlockwise.
And you get a diagram something like this(uploaded in the picture)
The dottel lines represent the "perpendicular" distance from the lines of forces to the pivot and the noticeably curved arrows represent the anticlockwise and clockwise moments in the picture.
You resolve the moments of forces in the question;
Torque = 5(2) + 10(2) -20(3)
therefore Torque = 10 + 20 -60
therefore Torque = -30 Nm Ans A
You take either anticlockwise moment or clockwise moment as the positive direction in the calculation of this question. In this case, anticlockwise moment of force is taken as the positive direction in the question. Answer is 30 Nm. Ans A

 

[Mustehssun Iqbal]

This question or a question like this has been also answered somewhere before in this thread. You can check it too if you want to.
And I suggest you redo this question too.

 

[Mustehssun Iqbal]

View attachment 6427

Assalamu alaikum,
Young modulus = stress/ strain
therefore Young modulus = F/A/delta l/l
therefore Young modulus = Fp l/A delta l
therefore E = Fpl/delta l => Fp = A delta le/l
Young modulus is represented by E and Fp represents the Force on wire P;
therefore E = Fq (2l )/(A/2) delta l => Fq = EA delta l/4l
therefore Fp/Fq = A deltaE/l/AE delta l/4l
therefore Fp/Fq = 4 Ans D
p.s. check your marking scheme : )

 

[Mustehssun Iqbal]

View attachment 6429

Young modulus = Stress/Strain
E = F/A/delta l/l
therefore E = 60/pi r^2/delta l/l
therefore E = 60/pi (d/4)^2/delta l/l
Equating both the Young modulus, since the wire is of the same material;
therefore 60/pi r^2/delta l/l = 60/pi r^2/32/l/4
therefore l = 8mm Ans C
Note: In this question, the value of extensions are put in mm instead of metres. The answer gained is also in mm.
l = 8 mm Ans C

 

[rideronthestorm]

Thanks.in the 1st question u answered , How do we know which ones clockwise and which ones anticlockwise :/ ? and why are we doing 10x2 the pivot distance is 4 from the 10n force ...

 

[rideronthestorm]

can u answer the other questions too plz ?

 

[ABDSyed]

Any Genious Here Giving A2
PLZ Help Me

 

[rideronthestorm]

the remaining ones from before and these too

 

[rideronthestorm]

 

[rideronthestorm]

 

[rideronthestorm]

 

[rideronthestorm]

 

[rideronthestorm]

 

[rideronthestorm]

 

[rideronthestorm]