!! Physics HL LC '16 - Predictions, guesses, discussion, etc.

Misty_01

adam240610 wrote: »

It says a flat disk, so the friction is just pointing towards the centre of the the circle. It can go to the left or right it doesn't matter.

The child remains stationary as there is no friction between him and the merry go round, like if you put the child one ice and spun it, he wouldn't move with the ice. Its a stupid question.

I still don't get it ! Friction opposes movement , the centripetal force is towards the centre so why can we point it towards the centre ???

What do you mean if we put the child on ice and spun it the child wouldn't move ?? How does friction cause the child to move with the merry go round ?? How does friction allow us to walk ??

adam240610

Misty_01 wrote: »

I still don't get it ! Friction opposes movement , the centripetal force is towards the centre so why can we point it towards the centre ???

What do you mean if we put the child on ice and spun it the child wouldn't move ?? How does friction cause the child to move with the merry go round ?? How does friction allow us to walk ??

Say you have a record player, if you put something on the record as it goes around it will move towards the outside and fall off, the motion of the object on the record travels outwards, and friction opposes this movement and hence acts in the opposite direction

It's kind of hard to explain, look up a video on friction on youtube, it should help with the basics. https://www.youtube.com/watch?v=fo_pmp5rtzo

WorthlessPeon

Can you use either the mechanical or the electrical method when finding the specific heat capacity of a metal/water?

Misty_01

adam240610 wrote: »

Say you have a record player, if you put something on the record as it goes around it will move towards the outside and fall off, the motion of the object on the record travels outwards, and friction opposes this movement and hence acts in the opposite direction

It's kind of hard to explain, look up a video on friction on youtube, it should help with the basics.


Thanks, I watched the video. So is it the friction that makes the object move in a circle with the record and keeps it fixed on the record ???the object itself is stationery but it is being moved by the record player ??? Do I have the right idea here ??

Also for the last bit to the question , if the friction is gone shouldn't it just fly out ?

Thanks so much for all your help , I really appreciate it.

adam240610

Misty_01 wrote: »

adam240610 wrote: »

Say you have a record player, if you put something on the record as it goes around it will move towards the outside and fall off, the motion of the object on the record travels outwards, and friction opposes this movement and hence acts in the opposite direction

It's kind of hard to explain, look up a video on friction on youtube, it should help with the basics.


Thanks, I watched the video. So is it the friction that makes the object move in a circle with the record and keeps it fixed on the record ???the object itself is stationery but it is being moved by the record player ??? Do I have the right idea here ??

Also for the last bit to the question , if the friction is gone shouldn't it just fly out ?

Thanks so much for all your help , I really appreciate it.

Yeah that's the right items. It doesn't fly out as there is no friction to exert any force to the child, so nothing happens. The last part of the question is completely stupid in the first place anyways.

Misty_01

Does anyone know where I can get the mass of atom (u) in log tables ??? E.g on pg 83

TomDelahunt

Misty_01 wrote: »

Does anyone know where I can get the mass of atom (u) in log tables ??? E.g on pg 83

The U value is on page 47, if that's what you're looking for?
muliply the values stated for mass on back pages by this to find the mass of the atoms you're looking for

adam240610

If it's required it'll nearly definitely be on the paper itself.

How are people feeling for this exam?

Geoffrey90

Heat transfer could definitely be a long question this year since it hasn't come up in a few years. I'm predicting that you might have to draw a diagram of a fridge and explain how it gets rid of heat, and maybe a maths question on heat transfer too. Similar to what came up for the mocks

Misty_01

TomDelahunt wrote: »

The U value is on page 47, if that's what you're looking for?
muliply the values stated for mass on back pages by this to find the mass of the atoms you're looking for

Thanks Tom but I forgot to add for a neutron , I can find all the atoms and their isotopes but not the neutron which I found in an exam q. Thanks!

Seaaan

Misty_01 wrote: »

Thanks Tom but I forgot to add for a neutron , I can find all the atoms and their isotopes but not the neutron which I found in an exam q. Thanks!

Page 48 gives its mass relative to electron

adam240610

Same mass as a proton anyways, same charge on an electron as a proton too. (Opposite charge I mean obviously)

Bazinga_N

Our teacher never covered any of Magnetism or Electromagnetism with us in class (chapters 26, 27 & 28 in Real World Physics). Obviously I'm not gonna be able to do it in a night but I was wondering if there are any definitions/laws I could learn tonight for the short questions as I'd prefer not to be limited for Question 5? Any help is appreciated!

lc16_

Bazinga_N wrote: »

Our teacher never covered any of Magnetism or Electromagnetism with us in class (chapters 26, 27 & 28 in Real World Physics). Obviously I'm not gonna be able to do it in a night but I was wondering if there are any definitions/laws I could learn tonight for the short questions as I'd prefer not to be limited for Question 5? Any help is appreciated!

The definition/laws from those chapters are;
-Magnetix flux density
-Tesla
-Weber
-Electromagnetic Induction
-Laws of EM Induction : Faradays & Lenzs
-Transformer
-Inductors
-Ampere
You should be covered for the Q5s!

Brian_R

Bazinga_N wrote: »

Our teacher never covered any of Magnetism or Electromagnetism with us in class (chapters 26, 27 & 28 in Real World Physics). Obviously I'm not gonna be able to do it in a night but I was wondering if there are any definitions/laws I could learn tonight for the short questions as I'd prefer not to be limited for Question 5? Any help is appreciated!

you probably could do it in a night it's not all that long

ella1998

Hopefully someone can help me here, so with some defintions i just give notation, but im not sure how much info i should give with each letter. eg E=F/q, would i get full marks by saying:
E=electric field strength, F= force and q =charge, or do i have to be more specific?

lc16_

ella1998 wrote: »

Hopefully someone can help me here, so with some defintions i just give notation, but im not sure how much info i should give with each letter. eg E=F/q, would i get full marks by saying:
E=electric field strength, F= force and q =charge, or do i have to be more specific?

I always mention the units in what they're measured aswell just in case.

adam240610

ella1998 wrote: »

Hopefully someone can help me here, so with some defintions i just give notation, but im not sure how much info i should give with each letter. eg E=F/q, would i get full marks by saying:
E=electric field strength, F= force and q =charge, or do i have to be more specific?

In the vast majority of cases you'll be fine if you include units as well, if they need to remark papers they may exclude those types of definitions and take word definitions to reduce grades, but it's unlikely.

Edrees98

A circuit with resistors is due up this year for sure!

adam240610

Edrees98 wrote: »

A circuit with resistors is due up this year for sure!

A lot of circuits have resistors I believe :pac:

Edrees98

adam240610 wrote: »

A lot of circuits have resistors I believe :pac:

Haha true but a question like 2005 question 8 I think.

legocrazy505

So tough on my brain to remember all the physics and all the accounting right now.

Edrees98

legocrazy505 wrote: »

So tough on my brain to remember all the physics and all the accounting right now.

Just keep calm, you've done all the study. Being nervous will just make you forget the information.

adam240610

legocrazy505 wrote: »

So tough on my brain to remember all the physics and all the accounting right now.

You could be doing spanish and chemistry on tuesday too, I know one guy that has 5 subjects in a row now.

Sure those resistor questions are great anyways, wouldn't complain in the slightest.

legocrazy505

Edrees98 wrote: »

Just keep calm, you've done all the study. Being nervous will just make you forget the information.

About 70% of the physics course comes pretty quickly to me. The problem with this timetabling though is if you do both you are going from one subject heavy on theory and mathematical based questions to another subject also heavy on theory and mathematical based questions. Would have much rather have them on two separate days.

Edrees98

adam240610 wrote: »

You could be doing spanish and chemistry on tuesday too, I know one guy that has 5 subjects in a row now.

Sure those resistor questions are great anyways, wouldn't complain in the slightest.

They are fun but most people don't have a clue about how to solve them.

adam240610

Edrees98 wrote: »

They are fun but most people don't have a clue about how to solve them.

SEC needs most people getting C's so

legocrazy505

Please no electricity. I hate electricity. I can't even remember colours of cables in plugs. Electricity has always been my weak spot in physics.

A97

legocrazy505 wrote: »

So tough on my brain to remember all the physics and all the accounting right now.

You'll survive. It's a heavy day for sure but if I can get through it with two A's, you can too! Just give Physics your best shot and then you can completely forget about it.

Make sure to get a good night's sleep, to keep hydrated and to get a good breakfast and meal between the two.

Keep your basic needs in good condition and the adrenaline will get you through it.

adam240610

legocrazy505 wrote: »

So tough on my brain to remember all the physics and all the accounting right now.

Watch game of thrones between them sure