Physics P-22 GT.

[Ben Callum]

People really messed up the electricity part threshold will be around 35

 

[xtremeuser12345]

Stress = Force/Area, right?
Force was the same for both but the areas were different.
For P the area was : 1/4(pie)(d^2)
For Q the area was : (pie)(d^2)
Apply the formula, with P ABOVE Q, i'm pretty sure you can do the math after that
The answer you'll get is P:Q = 4:1

I'm not quite sure about the second part but it was either 1:2 or 2:1. How?
Suppose the extension in P was e, so strain in P = e/original length
now here's the confusing part, i don't know what was the extension in Q it was either (1/2)e or 2e. Anybody here who can help me with this?
First i did it with (1/2)e i got the ratio 2:1 but for some reason i cancelled it and took 2e as the extension finally arriving at the ratio 1:2. There's no third answer to it i'm sure

surely the extension in Q is 1/2 e.since Q is bigger having much bigger cross section,Q will have less extension hence less strain so only 2:1 makes sense.

 

[xtremeuser12345]

What did the question say? That we had to give in terms of brightness and the number of fringes? Are you sure it said that

it said state the changes to the fringes hence include everything.

 

[Snowysangel]

it said state the changes to the fringes hence include everything.

So how is writing that they are formed at a greater angle not acceotable?

 

[xtremeuser12345]

So how is writing that they are formed at a greater angle not acceotable?

the angle that they make isnt related to them.check the ms the question came many times i never saw anything about the angle but i dont know im not an examiner myself

 

[Snowysangel]

surely the extension in Q is 1/2 e.since Q is bigger having much bigger cross section,Q will have less extension hence less strain so only 2:1 makes sense.

Extension is proportional to the cross sectional area and not the diameter. So cross sectional areas were pi(d/2)^2 and pi d^2 or pi d^2/4 and pid2...hence the stress and strain were both the same ie 1 : 1/4

 

[Snowysangel]

the angle that they make isnt related to them.check the ms the question came many times i never saw anything about the angle but i dont know im not an examiner myself

It means that they're farther away from the oth order of maximum...the questions were about the wavelengths of light? Cause I've seen questions about the changes in slit separation, width of slit, distance from screen but just once about the change in wavelength, and they mentioned the angle. Anyway I could be wrong. Lets all just pray that we all get a good grade

 

[guest1234]

Stress = Force/Area, right?
I'm not quite sure about the second part but it was either 1:2 or 2:1. How?
Suppose the extension in P was e, so strain in P = e/original length
now here's the confusing part, i don't know what was the extension in Q it was either (1/2)e or 2e. Anybody here who can help me with this?
First i did it with (1/2)e i got the ratio 2:1 but for some reason i cancelled it and took 2e as the extension finally arriving at the ratio 1:2. There's no third answer to it i'm sure

Well.....infact there is.
Think logically. strain = stress/Young Modulus......right? The material was the same in both cases, which implies that Young Modulus is constant. Both wires also had the same original length. So if stress in P is 4 times the stress in Q, the strain in P is also 4 times the strain in Q. It's as simple as that.

 

[xtremeuser12345]

It means that they're farther away from the oth order of maximum...the questions were about the wavelengths of light? Cause I've seen questions about the changes in slit separation, width of slit, distance from screen but just once about the change in wavelength, and they mentioned the angle. Anyway I could be wrong. Lets all just pray that we all get a good grade

it said that "a redlight is used instead,state the changes to the fringes"not the differences between the wavelengths

 

[Snowysangel]

it said that "a redlight is used instead,state the changes to the fringes"not the differences between the wavelengths

Yup and I wrote that the angle at which the fur he's are formed will be greater. The angle has nothing to do with the wavelength, sintheta is just directly proportional to it. I dunno what you're saying btw

 

[Snowysangel]

it said that "a redlight is used instead,state the changes to the fringes"not the differences between the wavelengths

The wavelength of Red light is 7x10^-7 and the wavelength of the laser was 450x10-7 so yeah it indirectly stated the difference in wavelengths

 

[xtremeuser12345]

The wavelength of Red light is 7x10^-7 and the wavelength of the laser was 450x10-7 so yeah it indirectly stated the difference in wavelengths

arguing here wont help anything just wait till the ms is out,and the wavelength was 450x10^-9 not 450x10^-7

 

[Snowysangel]

arguing here wont help anything just wait till the ms is out,and the wavelength was 450x10^-9 not 450x10^-7

Yeah that's what I meant but they were comparing the wavelengths not their laser-nature cause if didn't say anywhere that the red light wasnt to be a laser..okay let's stop and discuss possible mcq questions instead!

 

[Afzal1]

i got stress 1/4 and starin 4

exactly.... at last sm1 comes up with the rite answer

 

[kitkat <3 :P]

exactly.... at last sm1 comes up with the rite answer

and y do u think its the right anwer ._.

 

[Afzal1]

Well.....infact there is.
Think logically. strain = stress/Young Modulus......right? The material was the same in both cases, which implies that Young Modulus is constant. Both wires also had the same original length. So if stress in P is 4 times the stress in Q, the strain in P is also 4 times the strain in Q. It's as simple as that.

my answers
1)Am-1k-1
2)1.25*10^4 uncert 775 (6.2% of 1.25*10^4)
the acceleration was 2.6, 169N, 49N
3) 180, 22.9, 90, 90
4) 1:4 and 4:1
5) 24-(2.4*6) = 9.6 , 4ohms, 68.6 W
6) i dont remeber

 

[kitkat <3 :P]

my answers
1)Am-1k-1
2)1.25*10^4 uncert 775 (6.2% of 1.25*10^4)
the acceleration was 2.6, 169N, 49N
3) 180, 22.9, 90, 90
4) 1:4 and 4:1
5) 24-(2.4*6) = 9.6 , 4ohms, 68.6 W
6) i dont remeber

for area i used the formula pi*(d^2)/4 ._. thats how i got the answer
and my answers matrch urs to some extent

 

[Afzal1]

and y do u think its the right anwer ._.

see the stress = F/a and since A=d^2
so for p (it is f/d^2) and for q(f/4d^2) so rtio is 1:4

strain = stress / young modulus
since it is same material the E is same
so 1/E FOR P
AND 4/E FOR Q
SO IT IS 4:1

 

[Afzal1]

for area i used the formula pi*(d^2)/4 ._. thats how i got the answer
and my answers matrch urs to some extent

how many of them match

 

[kitkat <3 :P]

see the stress = F/a and since A=d^2
so for p (it is f/d^2) and for q(f/4d^2) so rtio is 1:4

strain = stress / young modulus
since it is same material the E is same
so 1/E FOR P
AND 4/E FOR Q
SO IT IS 4:1

exactly my logic