Physics: Post your doubts here!

[Metallic9896]

What about the graph question which was a friction less slope?

It was A vs. C and then A cause C implied a greater final velocity than initial but that's impossible since no input from any force and mgh was the same as it came back to same height as it initially had, so had to be A.

 

[Zaki ali asghar]

I did A at first too but if you had looked closely the point S was at lower level than the original point from where it started so the loss in pe was converted to Kinetic energy hence the greater speed.

 

[Metallic9896]

I did A at first too but if you had looked closely the point S was at lower level than the original point from where it started so the loss in pe was converted to Kinetic energy hence the greater speed.

If you're absolutely sure then you're right.

 

[amina1300]

"That q about sqrtmgh was C, the sum of m sqrt 2gh1 and m sqrt 2gh2"
and "the The one about air resistance was C, the scary looking equations. I got it wrong"

How can they be C?

 

[amina1300]

What about the phase difference question?

 

[amina1300]

The question with the 10 revolutions per second and we had to find wavelength of wave ??

 

[Metallic9896]

"That q about sqrtmgh was C, the sum of m sqrt 2gh1 and m sqrt 2gh2"
and "the The one about air resistance was C, the scary looking equations. I got it wrong"

How can it be C both of them?

These were two separate questions or at least I'm referring to separate ones in my answer above lol. The first one was the object falling height h1 then bouncing back up to h2 so what was change in momentum.

Change in momemtum is final momemtum - initial momemtum, but since the velocities will be in opposite direction, if you take downwards as negative and upwards as positive, final - initial = m(v2 - (-v1)) = m(v2 + v1)

So only C was giving that and you get v by the sqrt 2gh by 2as = v squared - u squared and assuming u squared to be zero in initial and v squared to be zero in final

As for the air resistance one I don't remember the explanation but my friend explained it clearly and it was C

 

[Metallic9896]

The question with the 10 revolutions per second and we had to find wavelength of wave ??

10 revolutions in 1 second
50 teeth in 1 revolution
1 teeth = 1 Hz for that metal strip thing
50 x 1 = 50 Hz in one revolution if one revolution per second
10 x 50 = 500 Hz in ten revolutions if ten revolutions per second

v = f x wavelength
330 was v
330/500 = 0.66m

 

[Metallic9896]

What about the phase difference question?

I did lambda/4 for the one in which phase difference was 90 degrees and we had to find potential wavelength difference

I did 180 degrees and 'same' amplitude, they'd be oscillating with opposite displacements but since amplitude is a scalar quantity it would be the same, for the question prior to that in which they asked about two antinodes or any other points that are half a wavelength apart (excluding nodes of course)

 

[amina1300]

Yay these 3 questions are correct!

 

[Metallic9896]

Yay these 3 questions are correct!

haha yayy!

 

[shahzaib ihsan]

only people in this forum wronged my 5 questions! i don't know how many more..

I did A at first too but if you had looked closely the point S was at lower level than the original point from where it started so the loss in pe was converted to Kinetic energy hence the greater speed.

i am absolutely sure that the second slope ( the one in which the ball fall) was more steep in the picture, as well as the graph of 2nd slope was steeper than first ones

 

[amina1300]

What was the load unload graphs answer?

 

[shahzaib ihsan]

What was the load unload graphs answer?

what did you choose

 

[Metallic9896]

What was the load unload graphs answer?

Definitely A. I chose D. But for sure it was A after discussions.

 

[Zaki ali asghar]

one of the momentum questions was repeated in which there was something like m1gh1 type ans was B

 

[Zaki ali asghar]

Yep the load unload was A.you had to either subtract larger triangle area-smaller area or the trapzeium area

 

[shahzaib ihsan]

now 6 wrong.\.. gg

 

[Zaki ali asghar]

The repeats i remember so far Q2 the one about resultant force,the mircrometer one,the graph of what does x and y represent,the momentum change,the new deflection of electron,the scale one right below the forces in circle Q,the resistance one which had a factor of 16.

 

[Mstudent]

Just came back from my 9702 paper 11 exam, and Alhamdulilah it was really good