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Official OCR A G481 mechanics 20th May 2013

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Reply 320

skitz241

Original post by OllieGCSEs

Around 1.875x10^11?

I got 10^9 since it was giga?

Reply 321

seajamiet

Original post by Liberty.

I used F = kx, then substituted F into a = F/m
But now I can't remember anything else I did :confused:

Exactly what i did.

Reply 322

OllieGCSEs

Original post by skitz241

I got 10^9 since it was giga?

The Stress was in GPa but the strain was in %, so the strain was 0.8/100, i.e 0.008 or something

Reply 323

teamvezon10

Original post by OllieGCSEs

Sorry to hear that :frown:

I'm fairly sure i messed up the density question somehow so i can't help you with that

I just got told the question asked for deceleration! I just realised that I even wrote above; acceleration =gradient, displacement = deceleration, I've no idea why I worked out the deceleration! The nerves just made me mess up so much, IDEK, I can do so much better when not under stress. Was it deaccl or displacement?

Reply 324

Joeyoh9292

Okay so first post. I've just been talking to my teachers who had a look and they said it wasn't too hard, but it most definitely wasn't a walk in the park. We all found the first question quite simple once you understand it (bigger volume - smaller volume then simple maths). The harder questions were supposed to by deriving Ek = 1/2mv^2. You needed to substitute values until you get f=ma and w=fx. Sub in ma = f so you get Ek = max. 1/2mv^2 = max. 1/2v^2 = ax. Do suvat's to realise that ax = 1/2v^2. The moment's question was pretty simple. They're in equilibrium so the anticlockwise = clockwise. I can't remember the rest of the questions, but I for one am feeling pretty confident with this exam.

Reply 325

Joeyoh9292

Original post by OllieGCSEs

The Stress was in GPa but the strain was in %, so the strain was 0.8/100, i.e 0.008 or something

Yeah, that seems more correct. If you got the correct numbers, you should get 2 marks though (seeing as it was a 3 mark question). That's why I'm not so worried about this :smile:

Reply 326

-bethan-

Original post by RafJav

Did anyone else find that paper really hard or was it just me...

Thank goodness, I did and so did everyone else in my year :frown:

Reply 327

Layontheland

Original post by OllieGCSEs

Around 1.875x10^11?

I got exactly the same

Posted from TSR Mobile

Reply 328

Hawthorns

I missed ou the moments question and deriving kinetic energy (both 3 marks)

Reply 329

OllieGCSEs

Original post by teamvezon10

It was deceleration, but displacement is not equal to deceleration...acceleration is found using the gradient, and when the gradient is negative, you get negative acceleration which is also known as deceleration

Reply 330

OllieGCSEs

Original post by Joeyoh9292

Yeah, that seems more correct. If you got the correct numbers, you should get 2 marks though (seeing as it was a 3 mark question). That's why I'm not so worried about this :smile:

Precisely

nothing to worry about, seeing as 100% UMS is usually around 56-58

Reply 331

Joeyoh9292

Original post by Hawthorns

I missed ou the moments question and deriving kinetic energy (both 3 marks)

The deriving kinetic energy was more of an algebra question integrated with a solid understanding of Physics. It wasn't easy, so don't expect plenty of people to have attempted it (aka don't feel too bad :P)

Reply 332

Liberty.

I regret looking at this thread now!
I came out smiling, now I'm terrified until an unofficial mark scheme comes out which will probably make things worse anyway! :frown:

Reply 333

MrJiggly

Original post by -bethan-

Thank goodness, I did and so did everyone else in my year :frown:

For me, the hard part was the time. I was incredibly short on time :frown:

This headache didn't help either ¬_¬

Reply 334

Joeyoh9292

Original post by Liberty.

I regret looking at this thread now!
I came out smiling, now I'm terrified until an unofficial mark scheme comes out which will probably make things worse anyway! :frown:

Don't feel bad. Always remember that what's done is done. Worrying does nothing but knock your confidence, which isn't good during exam period. Keep your chin up.

Reply 335

AishM

Can someone do an unofficial mark scheme please?

Reply 336

-bethan-

Original post by MrJiggly

For me, the hard part was the time. I was incredibly short on time :frown:

This headache didn't help either ¬_¬

YES! I kept panicking looking at the clock, I'd have been fine if it was longer! Oh how horrible :frown:

I had an absolutely killer backache in my Maths exam last week, it's so annoying :mad:

Reply 337

JustFacts

Did anybody else work out the youngs modulas by finding the gradient of the stress /strain graph? I got 1.875X10-12 doing it that way. I didn't attempt the deriving k.e question and the moments question I think I got wrong. Apart from that it was ok, although i'm sure I dropped marks here and there.

Reply 338

Joeyoh9292

Original post by MrJiggly

For me, the hard part was the time. I was incredibly short on time :frown:

This headache didn't help either ¬_¬

I used to always get headaches during exams. Best thing is to try and consolidate yourself, drink water, and keep glancing at the clock after every question. If you realise you're stuck, move on. Headaches are usually brought on by pressure during exams and they distract you from work, but doing so will only increase the pressure due to time restraints. Just try to keep calm during exams, that's what I've practised.