physics exam (5 Viewers)

[Armenikum]

I got 38. something cm/s for the projectile q........

It was ok, better than chem, but I stuffed up the option (quanta to quarks).

Lol how did you stuff up quanta? It was sooo easy - thankgod there was nothing on leptons and quarks etc!

 

[anniea89]

I realy should not have come inot this post, because I'm looking over these multiple choice answrs and I get the feeling that I have screwed that part up badly.

 

[Armenikum]

I realy should not have come inot this post, because I'm looking over these multiple choice answrs and I get the feeling that I have screwed that part up badly.

Just remember a lot of people will do bad in multiple choice - they have some triccky ones!

 

[anniea89]

Lol how did you stuff up quanta? It was sooo easy - thankgod there was nothing on leptons and quarks etc!

I couldn't remember the stuff on de Broglie very well, so I couldn't answer the 7 mark question very well at all.

I basically did not know the option very well. I studied it, but had trouble recalling the information.

 

[farahodish]

I realy should not have come inot this post, because I'm looking over these multiple choice answrs and I get the feeling that I have screwed that part up badly.

LOLLLLLLLLLLLLL
i have said that after EVERY EVERY EVERY exam..

... yet im still doing it.

 

[Armenikum]

For question 14 - the p type semiconductor - where in the question does it say "IN ITS NATURAL ORIGINAL STATE'?

A property of a p type conductor is that it is positively charged during a voltage or when it absorbs a photon or whatever. The rest are wrong as the question broadly asks about a p type semi conductor in terms of state, but SPECIFICALLY asks for a property.


​

 

[Forbidden.]

LOLLLLLLLLLLLLL
i have said that after EVERY EVERY EVERY exam..

... yet im still doing it.

I soooo agreeee.

 

[emers43]

I couldn't remember the stuff on de Broglie very well, so I couldn't answer the 7 mark question very well at all.

I basically did not know the option very well. I studied it, but had trouble recalling the information.

im in the exact same boat. I think i died about 3 or 4 times during that exam. A hell of alot of fun though. lucky i do 13 units....

 

[Armenikum]

I couldn't remember the stuff on de Broglie very well, so I couldn't answer the 7 mark question very well at all.

I basically did not know the option very well. I studied it, but had trouble recalling the information.

Fair enough - I wrote 2 (large writing) pages on what he proposed and the Davison germer experiment with a drawing and also supporting Bohr's model - I think i am missing something, but in any case, I dont think id get the full 7 marks - but yea, ican see what you are saying with the 7 marker. Howd you go for the radioisotopes? Gift from god if you do Chemistry lol

 

[Shrikar]

That crappy little question...hated that. I'm convinced I have done something really wrong but here is what I had:

I had range at 80cm, at about 92cm (or there abouts). I worked out it took about 0.2 seconds for the ball to fall 30 centimetres (maybe it was 2-3...don't remember).

So, V = s/t was about 2-4 m/s.

So sorry I cannot remember ANY of the numbers I used. But this is the method I used. Was this stupid?

I used V^2 = U^2 +2aY
Where v= 0 at the top
U = ?
a = 9.8
Y = 110 (80+30)

Found U, then subed it into

v= u + at

Found time

Subed it into

X = U(x) X t

were X = 92 cm
T is known
U(x)= to be calculated

therefore u(x) = 19.8 ms-1

 

[Shrikar]

I got 38. something cm/s for the projectile q........

It was ok, better than chem, but I stuffed up the option (quanta to quarks).

Tell me about it, I screwed it up big time

 

[Forbidden.]

Did you get like 19.8 ms-1 for the horizontal velocity?

Obtain a value for t.

Δy = u_yt + 0.5a_yt²
u_y = 0 (There was no vertically projected initial velocity)
Δy = 0.5a_yt²

Δx = u_xt
u_x = Δx / t

Then I found my horizontal velocity was approximately 2 ms^-1

I used V^2 = U^2 +2aY
Where v= 0 at the top
U = ?
a = 9.8
Y = 110 (80+30)

Found U, then subed it into

v= u + at

Found time

Subed it into

X = U(x) X t

were X = 92 cm
T is known
U(x)= to be calculated

therefore u(x) = 19.8 ms-1

 

[anniea89]

Fair enough - I wrote 2 (large writing) pages on what he proposed and the Davison germer experiment with a drawing and also supporting Bohr's model - I think i am missing something, but in any case, I dont think id get the full 7 marks - but yea, ican see what you are saying with the 7 marker. Howd you go for the radioisotopes? Gift from god if you do Chemistry lol

That was a great question! I just used my chem stuff as well.

 

[Nosviper]

Here is what I remember about calculation questions

1) First Graph Question
* plotted the points and drew the curve
* Found the range at 80cm i think it was (not sure)

Find the Horizontal Velocity
* Since range = uxt
Range = value off the graph
t = found time by using y = ut +1/2at(2square)
Then subbed into the equation to get Ux
I remember converting my range to metres therefore I got 2.5ms roughly I remember. If you didnt convert your range to metres you must remember to keep your units as cms

2) Finding the Orbit from the Surface of Earth Geostationary
I forgot all about keplers Law of periods. I would have gotten extremely close to the correct answer and should get marks for working.
* correct way to do would be to use keplers law of periods and geostartionary satellite has 24 hour period and use that.
* I remembere the geostatioarny satellites orbit at 37500km then subtracted that distance from the radius of earth to get the orbit.

3) Finding the Velocity with mass increase of 0.37 (37%)
* needed to use the mass dilation formula
* didnt matter what values you substituted for mass as long as Mv was 37% larger than our Mo
* I inverted both sides to solve for velocity and I cant remember but I think i got 1.4 x10 to the something ms

4) Torque Question with Coul
Pretty sure I got this right.
* For part a the torque on the coil would cause a clockwise spin so a mass must be placed on the left of the circular piece (point x i think it was) to balance the torque
* For part b. To find the torque of a 0.2g mass i think it was. All you needed to do was convert it to metres then x 9.8 to get force. Using the formula T = fd with distance being the radius of the circule in metres.
* For part C. Using your answer from part b (pretend answer was 0.56nm)
Torques must equal each other therefore
0.56 = nBIA
Solveing for N I got 196 turns

5) Finding the Electric Field Strength of the point Charge
F = QE
E = F/Q
F = ma (sub in values from question to get force)
Q = given in the question
E = ... Vm-1 (cant remember answer)

Any more calculation questions I cant remember?

 

[ladystar]

I got like 3 ms-1 for that .. can't remember exact, ah well. Guess a slight difference in graph could make it a slight bit different, lets hope its right lol.
I think I got pretty much exactly double the amount of turns as you though. =/ (I remember it rounded to 400 or so) was the measurement a radius or a diameter?

about Q10 of multiple choice: sorry, made another thread - I'm pretty convinced that it should have been both A and C, makes no sense to seemingly ask for one property of waves and give both options.. http://community.boredofstudies.org/18/physics/157766/2-answers-multiple-choice.html

 

[Forbidden.]

Here is what I remember about calculation questions

1) First Graph Question
* plotted the points and drew the curve
* Found the range at 80cm i think it was (not sure)

Find the Horizontal Velocity
* Since range = uxt
Range = value off the graph
t = found time by using y = ut +1/2at(2square)
Then subbed into the equation to get Ux
I remember converting my range to metres therefore I got 2.5ms roughly I remember. If you didnt convert your range to metres you must remember to keep your units as cms

2) Finding the Orbit from the Surface of Earth Geostationary
I forgot all about keplers Law of periods. I would have gotten extremely close to the correct answer and should get marks for working.
* correct way to do would be to use keplers law of periods and geostartionary satellite has 24 hour period and use that.
* I remembere the geostatioarny satellites orbit at 37500km then subtracted that distance from the radius of earth to get the orbit.

3) Finding the Velocity with mass increase of 0.37 (37%)
* needed to use the mass dilation formula
* didnt matter what values you substituted for mass as long as Mv was 37% larger than our Mo
* I inverted both sides to solve for velocity and I cant remember but I think i got 1.4 x10 to the something ms

4) Torque Question with Coul
Pretty sure I got this right.
* For part a the torque on the coil would cause a clockwise spin so a mass must be placed on the left of the circular piece (point x i think it was) to balance the torque
* For part b. To find the torque of a 0.2g mass i think it was. All you needed to do was convert it to metres then x 9.8 to get force. Using the formula T = fd with distance being the radius of the circule in metres.
* For part C. Using your answer from part b (pretend answer was 0.56nm)
Torques must equal each other therefore
0.56 = nBIA
Solveing for N I got 196 turns

5) Finding the Electric Field Strength of the point Charge
F = QE
E = F/Q
F = ma (sub in values from question to get force)
Q = given in the question
E = ... Vm-1 (cant remember answer)

Any more calculation questions I cant remember?

1)
Forgot my answer.

2)
Found the radius after cube rooting it. Then I found the Height = Radius - Earth's radius.

Forgot my answer.

3)
I'm sure my answer had a magnitude of somewhere about 10⁷ ms^-1

4)
I got something within the 300 turns range.


5)
Forgot my answer too.
The unit can be NC^-1

 

[Shrikar]

Is that a good thing? Uh oh now I am worried

 

[Nosviper]

You must remember T = Fd is distance from the pivot axis. The torque or tunring moment on the circle would be the radius of the circle. Thats who you prolly got double the answer

 

[Forbidden.]

Is that a good thing? Uh oh now I am worried

I'm worried too !
I tried to minimize my amount of working out, I knew there should be 2 formulas used maximum hence the Δx and Δy formula.

 

[farahodish]

I got 392 turns
or something like that