Physics /12 Discussion!

[Obsidian Fl1ght]

yup its possible but I took stats 1 & 2 in 2 years for AS A2 level
I did take mechanics 3,4 stats 3,4 in 1 year though

Awesome. So it's a possibility.
I take it u like math?

 

[6Astarstudent]

Awesome. So it's a possibility.
I take it u like math?

yes very, I tend to like things i'm good at

 

[Obsidian Fl1ght]

1.2kg/m^3

Thanx.
Answer to this question was D

 

[Obsidian Fl1ght]

yes very, I tend to like things i'm good at

Don't mean to boast or sound so, but so do I.
Math can b fun.
*sigh* I've not encountered many ppl who think so
(Abt math)

 

[6Astarstudent]

Don't mean to boast or sound so, but so do I.
Math can b fun.
*sigh* I've not encountered many ppl who think so
(Abt math)

I guess I'm really lucky to have a class that's really enthusiastic about maths.
Nothing wrong with boasting when you really have that intelligence and ability!
I'm gonna head to bed, need some sleep. Exam is in 11hrs

 

[Obsidian Fl1ght]

I guess I'm really lucky to have a class that's really enthusiastic about maths.
Nothing wrong with boasting when you really have that intelligence and ability!
I'm gonna head to bed, need some sleep. Exam is in 11hrs

Thanks. Guess ur right. U shd call it as u see it.
Yeah... best of luck.

 

[Ikram Khaliq]

Someone just say it once and for all.

Q3.
Final answer A or C?

A. I messed it up. :/

 

[Ikram Khaliq]

so the model was 1/10 of original size
we know that young modulus = stress/strain
Y = (F/A)/(X/L) F=force, A=area, x=extension, L = original length
Y = FL/AX
X= FL/AY
so the dimensions of the load is shrinked by 1/10, so volume is 1/1000. density is the same so mass is 1/1000 and weight (force) is 1/1000
the original length is shrinked by 1/10
Area is shrinked by 1/100 because area = λr^2 and each r is 1/10 so 1/100
in short
F/1000
L/10
A/100
Y no change because same material

so X = (F/1000 x L/10 ) / (A/100 x Y) = FL/100AY
so original extension over new extension = 100

you are wrong, I'd say. Because they only asked us about stress. we did not have to deal with strain and hence, the original length. my answer was 10^1. I used the same calculations. such a crappy paper.

 

[6Astarstudent]

you are wrong, I'd say. Because they only asked us about stress. we did not have to deal with strain and hence, the original length. my answer was 10^1. I used the same calculations. such a crappy paper.

hm possibly, since I sat p13 instead of p12

 

[A*(a*)]

Wo

The answer for the force exerted when the wind hits the wall was 16000N.
CALCULATIONS: Force exerted by air was supposed to be calculated from newton's second law of momentum which is:
F = ϼAv^2
F = 1.2 x 12 x (33)^2
F = 15681N ≈ 16000N hence option D.

The answers for h1 and h2 of the mercury columns were 4 and 2.
CALCULATIONS: They asked the possible values of h1 and h2, not EXACT values.
Density of mercury is 13,600 kg/m3
Pressure = ρgh
h1 = 16000/13,600 x 9.81 = 0.12m
h2 = 8000/13,600 x 9.81 = 0.06m
Ratio
h1 : h2 = 2 : 1
In option A the values were 4 : 2 which is 2 : 1 hence the answer was A.

In a perfectly elastic collision the relative speed of approach is equal to the relative speed of seperation.

For a ball moving upwards with air resistance being neglected, the total energy of the system remains conserved according to the law of conservation of energy.


In question 3 the lines of actions of forces met at the centre, hence resultant force was coming out from the centre towards the 4N force (as resultant always acts closer towards component of greater magnitude).

These are confirmed answers.

Would it not be change in height = .12-.06 = 6 cm
And only one option showed this change of height, that was not what are you doing from ratios i guess. I am not confirmed though, but only 2 options had this change of height but we had to see that which height would be more by seeing what has lesser pressure. pls. correct me if I am wrong.

 

[Ikram Khaliq]

oh ok. i sat p12. I have bio tomorrow. haven't started it yet. so freakin' tired. last exam, yipee!

 

[talha196]

6 A* damn he can not be wrong

i also got 10^2
beta 5 A* lia hain gap nahi

 

[pakiboy]

The answer for the force exerted when the wind hits the wall was 16000N.
CALCULATIONS: Force exerted by air was supposed to be calculated from newton's second law of momentum which is:
F = ϼAv^2
F = 1.2 x 12 x (33)^2
F = 15681N ≈ 16000N hence option D.

The answers for h1 and h2 of the mercury columns were 4 and 2.
CALCULATIONS: They asked the possible values of h1 and h2, not EXACT values.
Density of mercury is 13,600 kg/m3
Pressure = ρgh
h1 = 16000/13,600 x 9.81 = 0.12m
h2 = 8000/13,600 x 9.81 = 0.06m
Ratio
h1 : h2 = 2 : 1
In option A the values were 4 : 2 which is 2 : 1 hence the answer was A.

In a perfectly elastic collision the relative speed of approach is equal to the relative speed of seperation.

For a ball moving upwards with air resistance being neglected, the total energy of the system remains conserved according to the law of conservation of energy.


In question 3 the lines of actions of forces met at the centre, hence resultant force was coming out from the centre towards the 4N force (as resultant always acts closer towards component of greater magnitude).

These are confirmed answers.

all correct
apart from the wind one!

 

[UziB]

Wo


Would it not be change in height = .12-.06 = 6 cm
And only one option showed this change of height, that was not what are you doing from ratios i guess. I am not confirmed though, but only 2 options had this change of height but we had to see that which height would be more by seeing what has lesser pressure. pls. correct me if I am wrong.

No, we had to see the ratio since they asked the possible values and not exact. You could even solve the question by using a derived gas law which in this case would've been P1/h1 = P2/h2 since ϼ and g were constants. If you simplify it this way you will also get h1:h2 = 2:1

 

[tanixx]

Distance in the train and markers question = 600m.
Person jumping from the air balloon and attaining terminal velocity = Option B i.e a graph of air resistance - time with an increasing curve and then a horizontal line.

was 600m option c or D ?

 

[razahayat777]

was 600m option c or D ?

D

 

[FRENZYAMU]

Someone just say it once and for all.

Q3.
Final answer A or C?

it ws A, cuz the angle with horizontal ws 36 degrees of the 5 N force, and measuring it thru a protractor meant that it ws A (i think it ws A that ws making an approx 36 degrees)

 

[A*(a*)]

No, we had to see the ratio since they asked the possible values and not exact. You could even solve the question by using a derived gas law which in this case would've been P1/h1 = P2/h2 since ϼ and g were constants. If you simplify it this way you will also get h1:h2 = 2:1

Okay but,
what's wrong with my method

 

[A star]

D

my method is the best ini mini minee moo and i got it right xD

 

[pakiboy]

thats actually just my goal
last year when I took my A levels I only got 4 A* 1A, 1B
6A* is my goal this year!

u arent happy with 4A* and 1A ? why bro u can get scholarship any where around the world!
thnks for stress ratio one i thought 10^2 is wrng