Higher Level Physics

.:FuZion:.

WolfForager wrote: »

Hmm, i'm not doing electricity at all.. It's a horrible, HORRBILE topic and deserves to be torn out of the curicculum and thrown off a very high cliff.

:pac: :pac: :pac:. Its not 100% evil. If you actually learn the definitions and demo experiments, its easy to get the first 2 / 3 parts. Granted thou that the 20 odd mark part is hard, always is.

Also in the Section A experiments, there isint a whole lot to learn.

WolfForager

I know a handful of electricity experiments actually.. Thought it would be best to know those just incase. Overall i just hope to pass this exam, i'm the only person in my class doing higher lol.

.:FuZion:.

WolfForager wrote: »

I know a handful of electricity experiments actually.. Thought it would be best to know those just incase. Overall i just hope to pass this exam, i'm the only person in my class doing higher lol.

Exactly. Sure thats a bloody achievement in itself lol. :P

celtic723

its amazing how people can just ignore you isnt it.:(

.:FuZion:.

celtic723 wrote: »

its amazing how people can just ignore you isnt it.:(

Sorry..

celtic723 wrote: »

can someone show me how to do Q7 the maths parts 2002 Revised Sample Paper

I could be wrong, but meh lol.

Calculate the electrical energy supplied:

By reading, we see that it has a power rating of 650W. 1W = 1 Joule per second. Therefore, there is 650 Joules per second being supplied to the microwave. Its running for 2 minutes ( 120 Seconds ) so we multiply 650 by 120 to get the total energy supplied.

78000 Joules.

Calculate the energy absorbed by the water:

By reading the question, we see that there is 500cm^3 of water. Now, the density of water is 1000kg/m^3. So, there is 500g of water ( .5 Kg )

Using the formula: Q = mc(Delta T) we can get the energy absorbed by the water.

Q = Energy, m = mass of the water, c = specific heat capacity of the water, Delta T = the rise in temprature.

Q = (.5)(4180)(34)
Q = 71060j

Hence determine the percentage effiency of the microwave oven:

Power input = 650W
Power output: 71060j supplied to the water. Like said earlier, 1W = 1 Joule per second. So we divide by 120 seconds for the 2 minutes its running.

71060/120 = 592.17 joules per second.

Percentage effiency = Power output / Power input x 100

PE = 592.17 / 650 x 100
PE = 91.1 %


Im pretty sure thats all right. I could be wrong thou. Good question to ask, I hope one of these comes up as a long question.

celtic723

.:FuZion:. wrote: »

Sorry..



I could be wrong, but meh lol.

Calculate the electrical energy supplied:

By reading, we see that it has a power rating of 650W. 1W = 1 Joule per second. Therefore, there is 650 Joules per second being supplied to the microwave. Its running for 2 minutes ( 120 Seconds ) so we multiply 650 by 120 to get the total energy supplied.

78000 Joules.

Calculate the energy absorbed by the water:

By reading the question, we see that there is 500cm^3 of water. Now, the density of water is 1000kg/m^3. So, there is 500g of water ( .5 Kg )

Using the formula: Q = mc(Delta T) we can get the energy absorbed by the water.

Q = Energy, m = mass of the water, c = specific heat capacity of the water, Delta T = the rise in temprature.

Q = (.5)(4180)(34)
Q = 71060j

Hence determine the percentage effiency of the microwave oven:

Power input = 650W
Power output: 71060j supplied to the water. Like said earlier, 1W = 1 Joule per second. So we divide by 120 seconds for the 2 minutes its running.

71060/120 = 592.16 joules per second.

Percentage effiency = Power output / Power input x 100

PE = 592.16 / 650 x 100
PE = 91.1 %


Im pretty sure thats all right. I could be wrong thou. Good question to ask, I hope one of these comes up as a long question.

LEGEND!!!! thanks alot it was doing my nut in and because there's no marking scheme i had to ask someone and no better place than boards.

.:FuZion:.

celtic723 wrote: »

LEGEND!!!! thanks alot it was doing my nut in and because there's no marking scheme i had to ask someone and no better place than boards.

No probs. Yeah its killer the way they have no scheme for it. But not only that, they dont even give answers for that paper. :rolleyes:

Delta Kilo

To get the percentage efficiency, it is easier to just use the joules. You calculated at the start that the energy supplied was 78000 joules and the energy absorbed was 71060. 71060/78000 x 100 = 91.1%.

I think it is more straight forward and obvious to your method, but that is only my opinion. Do whatever way you are familiar with.

KokaNoodles

Im pretty sure thats all right. I could be wrong thou. Good question to ask, I hope one of these comes up as a long question.

Yeah, got the same answer :eek::eek::eek:

.:FuZion:.

Delta Kilo wrote: »

To get the percentage efficiency, it is easier to just use the joules. You calculated at the start that the energy supplied was 78000 joules and the energy absorbed was 71060. 71060/78000 x 100 = 91.1%.

I think it is more straight forward and obvious to your method, but that is only my opinion. Do whatever way you are familiar with.

Yeah I realised that after too. But I thought to myself that power is measured in Watts and not Joules, so you might lose marks? Even thou its the right answer.

KokaNoodles wrote: »

Yeah, got the same answer :eek::eek::eek:

Thank god! :pac:

english4490

i'm going to fail physics!:(

jelomulawin

english4490 wrote: »

i'm going to fail physics!:(

lol, me 2, as i stated on my thread xDxD

english4490

jelomulawin wrote: »

lol, me 2, as i stated on my thread xDxD

why the hell did i do this subject! i have only started srudying it tonight!!

almostnever

I'm starting to freak out a little. I've never really taken it all that seriously as a subject as there were only two of us in the class (continuing the trend in our girls' school :rolleyes:) so it feels odd that I have to do the exam now I'm only learning definitions and experiments out of mechanics...might leave it altogether actually and see what happens. They're the easiest experiments to remember,IMO. Going to gun at electricity,love that topic and hopefully the questions will be reasonable!

WolfForager

You love electricity???!!!

*Makes a cross with fingers and moves away slowly*

almostnever

Yeah :$ I know that's probably weird,but my teacher is the same guy I had in first year tech and Junior Cert science,and he teaches Leaving Cert Technology now. He always stressed its importance,even in Junior cycle (I always knew I was going to do physics). Electricity and particle physics are my favourite

I'm actually really looking forward to doing the exam: it's the subject I find by far the easiest (for me). Not so much looking forward to chemistry on Tuesday, but I'll ignore that for now.

And +1 on the hating electricity thing: I'm completely leaving it out - it's just so boring.

almostnever

The thing I like about physics is that once you understand the concepts,you're pretty much done. Same applies in Chemistry but to a much lesser extent. Those pesky exceptions:rolleyes: I'm looking forward to these two,though. Economics,not so much.
Jammy,are you continuing to study physics after the Leaving Cert? (:

celtic723

Physics imo is woeful...i despise it tbh.. the definitions are a mouthful while the concepts are wrote in such a way as to confuse the unfortunate ones who are studying it. the only bit i enjoy is the Chemistry part of the course (Atom,etc)...sooner the better it's over and done with i should never have chosen it. Having said that i'm hoping for a B3 or B2.:D

almostnever

almostnever wrote: »

Jammy,are you continuing to study physics after the Leaving Cert? (:

Yah, I plan to do either theoretical physics or maths, hopefully. Going to go into it yourself?

celtic723 wrote: »

the only bit i enjoy is the Chemistry part of the course (Atom,etc.)

That's kind of ironic, really. You've the overlap mixed up. Partical physics (atom, etc.) is modern physics. The parts of the chemistry course that deal with radiation and the atom etc. are actually dealing with physics. And, infact, chemistry is technically a type of physics: I think of it as the application of/study of the effects of quantum electrodynamics (which is physics).

papu

Physics.... Why is there so much of it...

WolfForager

I know modern physics well... my knowledge of applied maths... about 15 experiements... Heat... Gonna look over waves before the night is out...

BRING IT ON!!!

CallMeDoctor

-JammyDodger- wrote: »

And, infact, chemistry is technically a type of physics: I think of it as the application of/study of the effects of quantum electrodynamics (which is physics).

How wrong you are...that is such a belittlement of a whole science. Stick to what u know..d two are completely different and individual.:eek: lol

errlloyd

Alright lads, lets look at this.

Section A.


Question 1 (Mechanics normally)


G by Free Fall (Graph of d against t^2, slope is acceleration)

Conservation of Momentum (m1u1 + m2u2 = m1v1 + m2v2)


Question 2 (Usually heat)


Boyles Law (Graph of P v 1/v)

Latent Heat of Vapourisation (Mass of water x SHCWater x DeltaTheta) + (Mass of Calirometre x SHCCopper x Delta Theta) = (MLv) + (Mass of of Steam x SHCWater x DeltaTheta)


Question 3 (Can be sound or Lenses, bet your mortgage its sound)


Speed of Sound in Tube (Graph of L v 1/f and 4x slope = speed of sound)

Natural Frequency and Length (Graph of F v 1/L)

Natural Frequency and Tension (Graph of F v Route T)


Question 4 (Always electricity)


Joules Law (Graph of DeltaTheta v I^2)

Resistivity of a piece of wire (P = R x A/L)



Remember guys

Women = Time x Money (It is well known women take up your time, and more time is more money)

Time = Money (Yes thats right it does)

So women = money^2

But

Money is the route of all evil

so women = (route evil)^2

so women = evil




Never say phsysics wasn't brilliant.

CallMeDoctor

CallMeDoctor wrote: »

How wrong you are...that is such a belittlement of a whole science. Stick to what u know..d two are completely different and individual.:eek: lol

I wasn't belittling chemistry.

So you're claiming that the field of chemistry doesn't fundamentally rely on the effects of quantum electrodynamics?

Edit: By the way, Errllyod: Boyle's law comes up in the mechanics experiments; so don't leave yourself with just latent heat of vaporisation for the heat experiment section.

errlloyd

Hmm they have no real option for heat tbh. SHC came up in 07 and Fusion came up in 08. Nothing has ever repeated from 2 years before, and even if SHC does, is there an easier experiment?

sock puppet

errlloyd wrote: »

Hmm they have no real option for heat tbh. SHC came up in 07 and Fusion came up in 08. Nothing has ever repeated from 2 years before, and even if SHC does, is there an easier experiment?

Is the calibration of a thermometer not a mandatory experiment?

errlloyd

Yeah it is, but there are no predictions for it from anyone. I think its just too easy. Like I have it highlighted in Orange (Which means secondary prediction), its the only exp other than Ohms law (debatable too hard?) that hasn't been asked ever.

sock puppet

sock puppet wrote: »

Is the calibration of a thermometer not a mandatory experiment?

Yah, it is. And, it has never came up.

From what I've been told, it's considered too simple to put up. Similar to the measurement of velocity and acceleration experiments (which haven't ever been up, either. Or the verification of Newton's second law exp., which is a bit simple too).

Cormac2791

physics is a bitch