** HL Physics Before / after **

ynwa14

Leaving Cert Student wrote: »

Does a vernier calipers measure diameter?

Yep

Leaving Cert Student

lisheen2308 wrote: »

here's a question from our pre which i think is nice:
The manager of a department store wants to purchase mirrors for the dressing room. To reduce costs, she wants to purchase mirrors that are short as possible but will allow a person of height 2m to see themselves standing full length in the mirror.
What is the shortest mirror she should purchase? justify your answer.

Anyone doing the applied electricity option, apparently not many schools do it?

1m?

no scope codgod

lisheen2308 wrote: »

Anyone doing the applied electricity option, apparently not many schools do it?

I'd say 95% of people do Particle Physics instead.

lisheen2308

Leaving Cert Student wrote: »

1m?

yup! that one caught me in the pre. Its just based on the laws of reflection

decisions

lisheen2308 wrote: »

yup! that one caught me in the pre. Its just based on the laws of reflection

+1

lisheen2308

anyone know how to calculate from a graph the speed of sound in air. I know the formula is C=4f(l+0.3d). But on the graph your given 1/f on the x axis and l/m on the y axis. not given a diammeter at all and asked to calculate that in the next part of the question.Also the graph doesnt go through the origin! why? im thinking its because the antinode is formed slightly outside the top of the pipe. Any help would be great. im guessing its something to do with slope?

Monsieur Folie

lisheen2308 wrote: »

anyone know how to calculate from a graph the speed of sound in air. I know the formula is C=4f(l+0.3d). But on the graph your given 1/f on the x axis and l/m on the y axis. not given a diammeter at all and asked to calculate that in the next part of the question.Also the graph doesnt go through the origin! why? im thinking its because the antinode is formed slightly outside the top of the pipe. Any help would be great. im guessing its something to do with slope?

I believe it's 4 times the slope but I'm not certain. It doesn't account for the +0.3d, but that's so small it's almost negligible. Your reasoning for it not going through the origin is correct also, I think.

lisheen2308

Monsieur Folie wrote: »

I believe it's 4 times the slope but I'm not certain. It doesn't account for the +0.3d, but that's so small it's almost negligible. Your reasoning for it not going through the origin is correct also, I think.

thanks for that, yeah i realise now if you just rearrange the formula in the form y=mx+c. you get L=(c/4)(1/f)-(0.3d) so yeah to get c it would be four times the slope. THANKS!

theoneguyy

Okay guys basically completely left revising physics til the last minute .
Anything I can focus on aswell as the experiments to get me through monday?

Monsieur Folie

theoneguyy wrote: »

Okay guys basically completely left revising physics til the last minute .
Anything I can focus on aswell as the experiments to get me through monday?

Know all experiments inside out. Know the electron and the modern physics section of the course as it comes up so, so much and is easier (imo) than the rest of the course. Know your option as it's a guaranteed question (you probably did Particle Physics).

After that, whatever you can fit in really.. Mechanics and/or electricity, but you probably won't have time to do both in detail at this point, so do the experiments from both and pick one to hone in on.

theoneguyy

Monsieur Folie wrote: »

Know all experiments inside out. Know the electron and the modern physics section of the course as it comes up so, so much and is easier (imo) than the rest of the course. Know your option as it's a guaranteed question (you probably did Particle Physics).

After that, whatever you can fit in really.. Mechanics and/or electricity, but you probably won't have time to do both in detail at this point, so do the experiments from both and pick one to hone in on.

Thanks a lot man:). Gonna be a lot a LOT of cramming today and tomorrow kinda serves me right though. Its not too bad cause physics is gonna be my 7th subject, don't know why I took it to be honest, still be nice to pass though

Monsieur Folie

Same here. Chemistry is my priority by a good bit since I want to do really well in chemistry. Physics is an afterthought, though I'm devoting my entire Sunday to refresh it all and go over my weak areas.

theoneguyy

Yeah hopefully it's not too bad. Good look anyway

Eurovisionmad

Goodness I'm starting to get quite nervous about Physics, I really don't want to mess up in it!

Undeadfred

Eurovisionmad wrote: »

Goodness I'm starting to get quite nervous about Physics, I really don't want to mess up in it!

same

MarieCurie22

Undeadfred wrote: »

same

Lads Im screwed!!!!!!!

Eurovisionmad

MarieCurie22 wrote: »

Lads Im screwed!!!!!!!

Ahhh but I bet you'd rock any radiation question though

Leaving Cert Student

Ah feck I was hoping to do well in this but there is loads I haven't got round to studying since the mocks

Monsieur Folie

Leaving Cert Student wrote: »

Ah feck I was hoping to do well in this but there is loads I haven't got round to studying since the mocks

Same.

MarieCurie22

Monsieur Folie wrote: »

Same.

will i have time to do all light 2m? and sound?

yoppo

I'm a mature repeat student doing physics for the first time so I'm worse off!

Really though, know the experiments well, Q5, option, nuclear physics, electron and mechanics and you should be fine!

I still have to run over heat, light and sound and I'm done!

yoppo

MarieCurie22 wrote: »

will i have time to do all light 2m? and sound?

Light is easy enough and so is sound so you should be fine!

Monsieur Folie

MarieCurie22 wrote: »

will i have time to do all light 2m? and sound?

I'm doing the whole course tomorrow. :P

MarieCurie22

yoppo wrote: »

I'm a mature repeat student doing physics for the first time so I'm worse off!

Really though, know the experiments well, Q5, option, nuclear physics, electron and mechanics and you should be fine!

I still have to run over heat, light and sound and I'm done!

Can i leave out the second half of electricity????please please please!!!!?

jamo2oo9

Would it be suicidal for not studying waves/sound? I hate that topic. I prefer to do heat/light/particle physics than that.

Monsieur Folie

jamo2oo9 wrote: »

Would it be suicidal for not studying waves/sound? I hate that topic. I prefer to do heat/light/particle physics than that.

It's not suicidal as long as you cover the experiments! But you will be potentially limiting your choice on the paper each time you leave something out!

yoppo

MarieCurie22 wrote: »

Can i leave out the second half of electricity????please please please!!!!?

What's the second half?

If your really stuck make sure you know the equations not in the log tables and use the marking schemes to give you an idea of questions and answers... attempt marks is better then nothing!

Chikablam

lisheen2308 wrote: »

here's a question from our pre which i think is nice:
The manager of a department store wants to purchase mirrors for the dressing room. To reduce costs, she wants to purchase mirrors that are short as possible but will allow a person of height 2m to see themselves standing full length in the mirror.
What is the shortest mirror she should purchase? justify your answer.

Anyone doing the applied electricity option, apparently not many schools do it?

My teacher said this question is flawed, as it all depends on how close you are to the mirror. If you're far away, you won't need as much, while being very close require a longer mirror

Leaving Cert Student

Chikablam wrote: »

My teacher said this question is flawed, as it all depends on how close you are to the mirror. If you're far away, you won't need as much, while being very close require a longer mirror

I thought this too, but if you place top of mirror at eye level, law of reflection says that looking at bottom of mirror (half your height) will show you your feet exactly. And this remains the same no matte how close/far away you are. Think about it... draw it out in 2d etc.

Raeral

Chikablam wrote: »

My teacher said this question is flawed, as it all depends on how close you are to the mirror. If you're far away, you won't need as much, while being very close require a longer mirror

Nah I'm pretty sure 1m is required no matter what distance you are from the mirror, so long as the top of the mirror is level with the top of your head. If you look at this image here, you see how, when the person looks halfway down the mirror ie 1m they see there feet as i=r: http://www.google.ie/search?newwindow=1&safe=off&q=length%20of%20mirror%20for%202m%20person&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=u928UdGKFo2g7AbDw4GwDg&biw=768&bih=928&sei=wt28UZeCGYXb7Aa3joCwAQ#biv=i%7C1%3Bd%7C9XONDC6G1cOCOM%3A