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National 5 Physics 2015-2016

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Original post by Ethan100
Dynamics and Space; The Velocity/Time Graphs section,

My class did a whole lesson on it.


I don't remember doing anything of that but if it's in the course i'm pretty much screwed :rofl:
Original post by sameehaiqbal
I don't remember doing anything of that but if it's in the course i'm pretty much screwed :rofl:


Don't worry, Hunter said it wasn't in the course either so I'm guessing its not. Its also not in the course Support notes !
Original post by Ethan100
Don't worry, Hunter said it wasn't in the course either so I'm guessing its not. Its also not in the course Support notes !


Can you teach me how to do half life please? I'm finding it difficult to understand :frown:
Original post by sameehaiqbal
Can you teach me how to do half life please? I'm finding it difficult to understand :frown:


There are two ways in which they can give you a half life question:

1. As a graph

Look at the highest point on the y-axis usually a measure of Activity in Bq and half that amount. Then go to that amount on the Y axis and find the value that corresponds with it on the x-axis which will be the time, this is the half life. To double-check you have the correct half-life, you can half that Activity value again and check the time it links to.

2. Given Numbers, E.g The Halflife of a radioisotope, The activity at the start and end, etc

If you are given the half-life, and an initial and final activity. And you are asked to calculate the time it takes for the source to decay to the final activity this is what you do.

Initial Activity : 1000000 Bq
Final Activity : 62500 Bq
Half Life : 8 hours

1000000/2 = 500000
500000/2 = 250000
250000/2 = 125000
125000/2 = 62500

As you can see it has taken 4 half-lives for us to get to the final activity from the initial activity,

8x4 = 32
(Used 8 because that is the half life)

Answer : 32 Hours

Hopefully you understand, There are some other ways of them doing the 2nd method but if you know the example above you can work them out.
(edited 7 years ago)
Do we need to know anything about Newtons Thought Experiment ?

Edit : When a switch is closed in a circuit does that mean current can pass through it ?
(edited 7 years ago)
Original post by Ethan100
Do we need to know anything about Newtons Thought Experiment ?

Edit : When a switch is closed in a circuit does that mean current can pass through it ?


No the Newtons Thought Experiment is at higher level.

Yes so if the switch is open theres a gap in the circuit which means current cant flow through it if the switch is closed the current can flow through it
Original post by Ethan100
There are two ways in which they can give you a half life question:

1. As a graph

Look at the highest point on the y-axis usually a measure of Activity in Bq and half that amount. Then go to that amount on the Y axis and find the value that corresponds with it on the x-axis which will be the time, this is the half life. To double-check you have the correct half-life, you can half that Activity value again and check the time it links to.

2. Given Numbers, E.g The Halflife of a radioisotope, The activity at the start and end, etc

If you are given the half-life, and an initial and final activity. And you are asked to calculate the time it takes for the source to decay to the final activity this is what you do.

Initial Activity : 1000000 Bq
Final Activity : 62500 Bq
Half Life : 8 hours

1000000/2 = 500000
500000/2 = 250000
250000/2 = 125000
125000/2 = 62500

As you can see it has taken 4 half-lives for us to get to the final activity from the initial activity,

8x4 = 32
(Used 8 because that is the half life)

Answer : 32 Hours

Hopefully you understand, There are some other ways of them doing the 2nd method but if you know the example above you can work them out.


I would rep you but I can't. Thanks so much!!! :biggrin:
Original post by sameehaiqbal
I would rep you but I can't. Thanks so much!!! :biggrin:


It's the least I could do for all the help you have given me :P
Hope the SQA don't use alien language on us or give weird questions!!!!!!!!
i was reading through these posts thinking I'm screwed as i have no idea what half of this stuff is and started stressing for quite a while.... but then i realised this is a national 5 physics thread and not a OCR GCE one I'm such a retard haha.
Original post by sameehaiqbal
Can someone please give an example of a half life question and talk me through how to do it? For some reason, I'm finding this difficult to understand...

Please somebody help :frown: i know it's getting late but I dont understand it at all and i am sure there will be loads of questions on half life


http://mrmackenzie.wikispaces.com/file/view/half_life_calculations.pdf
Original post by sameehaiqbal
Hope the SQA don't use alien language on us or give weird questions!!!!!!!!


This year the SQA have been loving problem solving questions :frown:
Good luck guys!!!!!!!
Btw I'll be in school really early so if anyones got last minute questions do let me know before 1pm :biggrin:

Hope your hard work pays off!! :biggrin:
Original post by dididid
i was reading through these posts thinking I'm screwed as i have no idea what half of this stuff is and started stressing for quite a while.... but then i realised this is a national 5 physics thread and not a OCR GCE one I'm such a retard haha.


Good luck anyways!!! :biggrin:
Hi guys! what do we need to know about space today? And nuclear reactors? Good luck to everyone!
If a question uses scientific notation should your answer also use scientific notation?
Good Luck everybody !
Do we get a relationship sheet?
Original post by Marina1264
Hi guys! what do we need to know about space today? And nuclear reactors? Good luck to everyone!


I reckon a question about re-entry could come up. Just know some benefits and risks of space exploration

Fusion - joining up of small nuclei to form a big one , fission - splitting to form two fission products and three neutrons, energy released, fission generates electricity, uranium and plutonium are some atoms that can be used in fission. Fusion occurs in stars.

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