Physics p22

[thunderingthunder]

wat was the wavelength for the last question????

 

[hassam]

640 to 2s.f

 

[sadman]

I made soooo much silly mistakes
first of all i completely forgot about G.P,E= mgh
second i idiotially didnt add all the resistance i added and deducted one.........stupid stupid me
i was runnig out of time and i forgot to multiply with 2 i didnt see it
and who knows what else i did!! i am sooooooooo sad

 

[mnabeel]

For the acceleration question, i got 9.79 ms^-2.. anyone got that? :S

used mg-F=ma

 

[sparten]

lets discuss 4m da very start
question 1
hw u ppl find out time to reach ground
and than final speed

 

[HamzaInam]

well i gat smthin else mine was like 4x10^-4...

 

[HamzaInam]

time for first question:well i messed it up i think...i used the formula s=ut+.5at^2..i dont know whether its right or not .....
what was the wavelength for last question?

 

[Sannikutti]

This is what i wrote for youngs modulous
Use two wires for eg one of them is test wire or controll wire and the other one is the wire ur testing it for youngmodelius
So use a weight measure it with help of newton meter and then apply to the wire.Measure the difference of the two wires by micrometer
Then Remove the weight
And repeat and make sure it is coming back to its orginal lenght and not plastically deformed
Then u measure the diameter of wire by micrometer and calculate the radius
Then using tht u calculate the crossection area and Force/Area =Stress
Then orginal lenght and extended lenght to calculate the strain
and then stress over strain to get youngs modulous of the wire
Know is this write
>Some one tell me pls!

 

[EzioAuditre]

time was 1.7s sthng
26.2 resultant velocity
6piDRv gives the resultant force acceleration was abt 4.sthng
wavelength 639nm
what was the phase differnece for the bright ones??

 

[HamzaInam]

does the error carry forward will come into account for the time question and mine wavelength was 320.....
what about the ressitivity force i used fcos30d.?

 

[HamzaInam]

what was the formula used for total current i used {V/R +(i/r + i/r)}
mine was smthing like 95a...wd the error carry forward earn me any marks???

 

[rahultaneja2010]

640nm was wavelength,
4.92 was acc. Of raindrop using volume of sphere, density formula and f=ma .... Must use weight of rainfdrop - friction = ma
Phase diff. Was 2 pi and pi
Kirchoff law as was 2.5 and 30
Youngs modulus qs need to plot force extension graph, get gradient and multiply by length/area
Light source qs I said 1 lamp is already coherant

Can't remember anymore ' hoping for 55 , I've done 20+ years of papers ... Trust me , gt will be 39 max for an A

Jai shree krishna

 

[gatechatl]

no...man see...u decreased the radius....so u decreased the volume...so mass decreased so its lighter....lighter means it ll reach terminal velocity earlier...cn u remind me of that F equation

That is the most flawed answer I have heard on these boards for a very long time. You made 2 assumptions that can't possibly be made. All you had to do was simply look at the formula they gave. You thought too much, and you are wrong.

Formula for resistive force : F=6(pi) DRv

You have decreased the radius>resistive force decreses> acceleration increases. No where in the exam did they day the rain drop lost mass. You look at the sure facts that they give, and you find the answer. Your assumptions are, for lack of a better word, stupid.

 

[boy2011]

phase difrence was pi and zero...nd hamzainam i thnk ul get e.c.f...i forgot to multiply by 2 in wavelength questn.hw much marks wl i lose?i thnk 1 mark?plx tel me....nd acc was 4.9 and tym in 1st questn was 1.7 nd velocity was 26.3 i thnk

 

[rahultaneja2010]

Phase difference was 2 pi/0 and pi ........... 2 pi for constructive

 

[sniper7137]

@HamzaInam i think you used the distance CP directly without doubling it. You had to double it to get the distance between the two bright fringes i.e. x in:
wavelength = (ax) / d. The phase difference was 2pi for bright one (constructive interference) and pi for the dark one (destructive interference).

 

[Hateexams93]

Am i the only one who got 2.6 for the current ?

 

[hassam]

no...man see...u decreased the radius....so u decreased the volume...so mass decreased so its lighter....lighter means it ll reach terminal velocity earlier...cn u remind me of that F equation

That is the most flawed answer I have heard on these boards for a very long time. You made 2 assumptions that can't possibly be made. All you had to do was simply look at the formula they gave. You thought too much, and you are wrong.

Formula for resistive force : F=6(pi) DRv

You have decreased the radius>resistive force decreses> acceleration increases. No where in the exam did they day the rain drop lost mass. You look at the sure facts that they give, and you find the answer. Your assumptions are, for lack of a better word, stupid.

....m=dv...in calculation of v(volume) u had to use radius.....ryt.......but i agree a will increase.. :good: ...so i guess u cn see how decreasing radius will decrease mass

 

[Hateexams93]

so if its mass decreases , its terminal velocity gonna be lower

 

[Hateexams93]

Am i the only one who got 2.6 for the current ?