*** Leaving Cert PHYSICS 2014 ***

Peregrine

qweerty wrote: »

Lol. I'd say the corrector will think you're such a prat. They'll be dying to deduct marks!

Why is that?

I can't think of any other way of doing it other than resolving the velocity.

Daniel2590

Out of curiosity for people who don't do applied maths and did q6, how did you do the part asking for max height?

EoghanIRL

aleatorio wrote: »

I said that, and said batteries are chemical based and capacitors are electrostatic



I did divide by two though?

You have to divide you final answer by 2. Each particle produces it's own gamma ray during pair annihilation .

EoghanIRL

Daniel2590 wrote: »

Out of curiosity for people who don't do applied maths and did q6, how did you do the part asking for max height?

Didn't do it but I would construct a triangle with theta as 15 degrees for a start . Then use trig . Could be wrong . Didn't even do it .

duignom

Daniel2590 wrote: »

Out of curiosity for people who don't do applied maths and did q6, how did you do the part asking for max height?

Not 100% on this. Can't remember the angle but it was like 23.
So I said the velocity on the y axis is usin23 (I think you had u from the previous part).
Acceleration on the y axis is -g. Use v=u+at to get t when v=0 (max height).
Sub t into an S equation.

aleatorio

EoghanIRL wrote: »

You have to divide you final answer by 2. Each particle produces it's own gamma ray during pair annihilation .

Yeah I mean I know that, I did that XD
Idk must have messed up somewhere :pac:

plmko

What a beautiful paper, thoroughly enjoyed it and I was delighted to see a whole nuclear fission question. Pity about particle physics being as question 11 though

EoghanIRL

plmko wrote: »

What a beautiful paper, thoroughly enjoyed it and I was delighted to see a whole nuclear fission question. Pity about particle physics being as question 11 though

Why ? It was much easier than normal .
They give you one of the answers in the diagram:P

aleatorio

What did everyone say for the difference between a laser and vapour lamp?

EoghanIRL

aleatorio wrote: »

What did everyone say for the difference between a laser and vapour lamp?

Hey . Inert gases vs mixture of gases is what my teacher said .

I personally wrote monochromatic for laser and not monochromatic for vapour lamp .

And I said something about their spectrums too.

Wasn't sure however .

aleatorio

EoghanIRL wrote: »

Hey . Inert gases vs mixture of gases is what my teacher said .

I personally wrote monochromatic for laser and not monochromatic for vapour lamp .

And I said something about their spectrums too.

Wasn't sure however .

I said something made up about frequencies and wavelengths ahaha oops :pac:

plmko

EoghanIRL wrote: »

Why ? It was much easier than normal .
They give you one of the answers in the diagram:P

Yeah I know that but I like a nice heavily maths based question on particle physics!

plmko

aleatorio wrote: »

I said something made up about frequencies and wavelengths ahaha oops :pac:

Same, I just said that lasers are one frequency of the light of the laser and vapour lamps are made up of frequencies of the elements that they are made of. And then I just said they have different wavelengths....YOLO

aleatorio

plmko wrote: »

Same, I just said that lasers are one frequency of the light of the laser and vapour lamps are made up of frequencies of the elements that they are made of. And then I just said they have different wavelengths....YOLO

I'm pretty sure they're both monochromatic so saying one wasn't wasn't an option I'd say :L
I said lasers had higher frequencies and shorter wavelengths :pac:

Nicke011

Solid_Shepard wrote: »

Just to nitpick for question 6, the net force is correct but your deduction is incorrect. As there is no net force it means that there is no acceleration, and, therefore, the trolley is at a constant velocity (the golfer is not necessarily stationary as it doesn't say it's at rest).

Sh*tttt, you're right!

MegGustaa

Solid_Shepard wrote: »

Just to nitpick for question 6, the net force is correct but your deduction is incorrect. As there is no net force it means that there is no acceleration, and, therefore, the trolley is at a constant velocity (the golfer is not necessarily stationary as it doesn't say it's at rest).

I said he could either be moving at a constant velocity or stopped but either way we know there is no acceleration because there's no net force acting on the system.

duignom wrote: »

Not 100% on this. Can't remember the angle but it was like 23.
So I said the velocity on the y axis is usin23 (I think you had u from the previous part).
Acceleration on the y axis is -g. Use v=u+at to get t when v=0 (max height).
Sub t into an S equation.

I essentially did the same - S(y) = u(y)t - gt^2, differentiate to get V(y) and put it equal to zero to get time of max height, then sub that back in.
The angle was 15 degrees. I had u as 63.6.

Edit - didn't see the part about people who don't do Applied Maths!
But I can't think of another way of doing it to be honest. You have to resolve the vector into x and y components and use mechanics equations.

Aspiring

How many uranium 235 nuclei were needed? :pac:

aleatorio

Aspiring wrote: »

How many uranium 235 nuclei were needed? :pac:

I got 7.628 x 10^24?
Converted the 202MeV to Joules, found 35% of that, converted 1GW to joules taking t as however many seconds are in a day, and divided one by the other

Aspiring

aleatorio wrote: »

I got 7.628 x 10^24?
Converted the 202MeV to Joules, found 35% of that, converted 1GW to joules taking t as however many seconds are in a day, and divided one by the other

Think I did the same :pac:

aleatorio

Aspiring wrote: »

Think I did the same :pac:

We must be right enough so :pac: sure most of the marks are the method :P

FatRat

Anyone know if gravity was a correct force in the last part in q1? I said gravity and I levelled the air track to avoid the force.

FatRat

aleatorio wrote: »

We must be right enough so :pac: sure most of the marks are the method :P

This is correct. What did you say for the function of moderator and fuel rods? And the heat exchanger for that matter?

Solid_Shepard

FatRat wrote: »

Anyone know if gravity was a correct force in the last part in q1? I said gravity and I levelled the air track to avoid the force.

Difficult to say. Weight (I am almost certain that gravity will be accepted too), friction, and air resistance are the most obvious forces to account for. I would think you'd be perfectly fine with that answer.

aleatorio

FatRat wrote: »

This is correct. What did you say for the function of moderator and fuel rods? And the heat exchanger for that matter?

Woohoo
I said Graphite, Boron and Heavy Water for examples of moderators
The moderator slows down fast neutrons to allow fission to occur
The control rods absorb neutrons and this control the rate of the reaction depending on how much of the rod is lowered into the reactor
For the heat exchanger I was a bit iffy, I wrote a waffley answer but basically said that it removes heat from one location and brings it to another place where it can be used to produce electricity - a liquid with a high heat capacity is circulated which absorbs head energy and is then brought to a cooler location where the heat is lost, leaving the reactor cooler (haven't a notion if that's right :pac:)

Daniel2590

aleatorio wrote: »

Woohoo
I said Graphite, Boron and Heavy Water for examples of moderators
The moderator slows down fast neutrons to allow fission to occur
The control rods absorb neutrons and this control the rate of the reaction depending on how much of the rod is lowered into the reactor
For the heat exchanger I was a bit iffy, I wrote a waffley answer but basically said that it removes heat from one location and brings it to another place where it can be used to produce electricity - a liquid with a high heat capacity is circulated which absorbs head energy and is then brought to a cooler location where the heat is lost, leaving the reactor cooler (haven't a notion if that's right :pac:)

You're thinking of control rods there I'm fairly sure.. I only gave deuterium as an example.

aleatorio

Daniel2590 wrote: »

You're thinking of control rods there I'm fairly sure.. I only gave deuterium as an example.

I googled it when I got home and it seems to be a thing :pac: I was unsure myself though XD

TheBegotten

Anyone else think that last part of the particle physics question to be rather sneaky? And the Beta - decay, I don't even think that's on the course!

LCMATHS

Solid_Shepard wrote: »

Difficult to say. Weight (I am almost certain that gravity will be accepted too), friction, and air resistance are the most obvious forces to account for. I would think you'd be perfectly fine with that answer.

I was going to say air resistance, but isn't air resistance just a type of friction?

EoghanIRL

Solid_Shepard wrote: »

Difficult to say. Weight (I am almost certain that gravity will be accepted too), friction, and air resistance are the most obvious forces to account for. I would think you'd be perfectly fine with that answer.

I said gravity and friction . Air resistance and friction would only be one point id imagine .

I would think weight is wrong . The body has weight even when the track is level . You are not trying to minimise weight but gravity . Not the same thing .
The whole idea of minimising gravity is to prevent acceleration not weight.

FHB

EoghanIRL wrote: »

I said gravity and friction . Air resistance and friction would only be one point id imagine .

I would think weight is wrong . The body has weight even when the track is level . You are not trying to minimise weight but gravity . Not the same thing .
The whole idea of minimising gravity is to prevent acceleration not weight.

Weight is the force that results from the action of gravity, so I'm almost certain that weight is correct(Probably more correct than gravity)

You need to have the air track level so that no component of the weight is acting parallel to the air track, which would result in acceleration down the track.