*Leaving Cert Applied Maths Thread*

rugrats

Could anybody do Q.2. I'd say I got about 5 marks in the whole section... I didn't get any of it... and that was the only section I studied last week

The rest of the paper was fairly doable. 1,4,5 and 10 especially. They were so straighforward

Undeadfred

It was tough i though. Lots of crazy answers. Very different paper to previous years. The even had a part c in question 10

ahmdoda

question 2 part b was just crazyly easy or i must have been wrong got 60 degree just by using the sin rule couldnt do part 2a though question 1 6 7 3 4 where grand 10 wasnt bad but messed up my 5 what did people get for e for 3 a ii

lostatsea

Aidan Roantree from the Institute says in the newspapers today that Question 6 (a) would have been undoable for many students because it included hydrostatics. This is nonsense - you didn't need to know anything about hydrostatics to do this question. They gave you an expression for how the force varies as it moves down through the water which is similar to the force in a string varying as its length changes. The main problem with this question is that they gave you the amplitude of 0.3 which wasn't needed to find the periodic time.

ahmdoda

lostatsea wrote: »

Aidan Roantree from the Institute says in the newspapers today that Question 6 (a) would have been undoable for many students because it included hydrostatics. This is nonsense - you didn't need to know anything about hydrostatics to do this question. They gave you an expression for how the force varies as it moves down through the water which is similar to the force in a string varying as its length changes. The main problem with this question is that they gave you the amplitude of 0.3 which wasn't needed to find the periodic time.

yes but the question put off ALOT of people once they saw a particle suspended in a fluid that 0.3 was a put off as well i dont know why they did that

lostatsea

ahmdoda wrote: »

yes but the question put off ALOT of people once they saw a particle suspended in a fluid that 0.3 was a put off as well i dont know why they did that

Fair enough - it was a little different that required a little thought but hardly undoable.

Roantree then bemoans the second part of Question 6. This was one of the nicest questions on the paper if you did statics. The last part was a gem.

Another teacher from Declan's called Christy Maginn thought the paper was fair which I agree with.

It wasn't an easy paper but having gone through Project Maths you should be prepared for little twists.

ahmdoda

lostatsea wrote: »

Fair enough - it was a little different that required a little thought but hardly undoable.

Roantree then bemoans the second part of Question 6. This was one of the nicest questions on the paper if you did statics. The last part was a gem.

Another teacher from Declan's called Christy Maginn thought the paper was fair which I agree with.

It wasn't an easy paper but having gone through Project Maths you should be prepared for little twists.

your right it was a very doable paper i guess roantree was just sympathizing with those that did bad and were complaining about the paper

allyb17

A lot of it just seems to be manipulation of formulae. This is another question which I got out, but I don't think I used the right method?

r is a vector of magnitude 10 units in a direction 70 degrees North of West.
s is a vector in a direction 10 degrees North of East.
Find the magnitude of s, correct to one decimal place, if (r+s) must be in a NE direction.
The answer is 15.8 but i'm a bit confused as to the method and why I got this answer.

Peregrine

It doesn't have to take that long, I just did it step by step.

allyb17

I did that out but got the wrong answer? it was approx. 13 but the actual answer is 15.8? I was just wondering why the I and J components are equal if in a NE direction? I don't understand that logic

allyb17

so 10sin70=9.4j
10cos70=-3.4i

9.4j-3.4i=r

9.4j + xsin10-3.4+xcos10= ycos80+ysin80 < I kind of guessed the 80 in a NE direction (10+70)?

Simulataneous Eqn:

9.4+o.98x=0.98y
0.98x-0.17y=3.4

0.98x-0.98y=-9.4
-0.98x+0.17y=-3.4

0.17-0.98=-0.81 / -9.4-3.4=-12.8

-0.81y=-12.8
y=12.8/0.81
y=15.8=magnitude of s

Now its the right answer but to be honest I don't see logic in it, I was hoping to get X=15.8 to be the magnitude of s not Y? can anyone help me understand this? Regards.

Peregrine

Don't guess the angle, also I don't understand how you got that simultaneous equation..


I don't think I made this clear, if they say NE direction (or NW, SW, SE) they meant EXACTLY North West. As in half way between North and West, 45° North of West.

If you look at any vector that's 45° from the horizontal, the i and j components have to be equal or else it won't make a perfect 45° angle + a right angle. Or look at an isosceles triangle with two 45° angles and a right angle (essentially the construction of a vector)



Also it works out as 15.8 for me:

(-3.42 + 0.9848x) i + (9.397 + 0.1736x) j

i = j

-3.42 + 0.9848x = 9.397 + 0.1736x
0.9848x - 0.1736x = 9.397 + 3.42
0.8112x = 12.87
x = 15.80004931
x = 15.8

allyb17

This helps so much, thank you

allyb17

Actually another question which Im finding extremely difficult, I can't afford a teacher so i'm trying to learn the course myself, its p 25 of Fundamental Applied Maths 2nd Edition.
Car travelling towards P at steady speed of 15m/s, accelerated at a constant rate between P and Q. At Q it reached 25m/s which was maintained until R.
If PR=980m and the time from P to R = 40 seconds, draw a time velocity graph of motion and calculate rate of acceleration.
Sorry to bug any of ye, but I though this would be the best place to ask? I have been trying for ages and at this stage have reached a mental block.

Peregrine

Have you drawn a velocity-time graph?

allyb17

I have my problem is getting the time taken for acceleration, it doesn't work out for me?

Peregrine

From that graph you can get this..



Solve for x. x is your time value from P to Q so t = whatever x is, u = 15 ms, v = 25 ms. Solve for a from there.

Undeadfred

How'd everyone do? I missed out on the A1, devastated

Eurovisionmad

I got an A2 which I'm reasonably happy with, I felt it was a bit of a weird exam in comparison to other years, but an A2 is what I needed in the overall scale

Prodigious

Only a B2, I'll be looking at it, but don't expect it to go up of course...

Monsieur Folie

I got a D1 which, considering I only answered not much more than half of the required amount of questions, is not too shabby! Almost annoyed I did prepare more questions in the end, but I passed and my goal was to pass so I'm happy!

My friend, who studied it properly, got an A1 too so he was happy!

bpb101

Got a D3. failed the mocks. main reason is i just didnt put in the effort. Would have taken it going into the exam. Done a graph for the question that had the ball boucing on the paper ( yea i know , not the way the wanted. ) Going to see what precentage i got and see what the examiner thought of my , how would you say , alterative method..
Congrats to the A1 lads and all those who got what they wanted. The real results will be on monday.

Undeadfred

The A2 rate this year is almost the same as the A1 rate, was it like that last year? I remember the A1 rate being a fair bit higher than the A2 rate last year

Peregrine

Guys what's the shortest chapter to do out of these.. (I'm not asking for the shortest chapters because I'm lazy)

I'm thinking of doing Q1-5, Q6 and Q10. I already have Q1 Uniform Acceleration done and over the past few weeks I've almost finished Q4 Pulleys and Wedges. Now I have 9 days left til 6th year and I was thinking of doing one more.

Initially I thought about doing Collisions (Chapters 6 and 7 in Murphy's new book?) but I don't think I'll get that finished in 9 days.

Can I finish Q2 Relative Velocity or Q3 Projectiles in 9 days if I work 2 hours a day?

Ompala

Nimrod 7 wrote: »

Guys what's the shortest chapter to do out of these.. (I'm not asking for the shortest chapters because I'm lazy)

I'm thinking of doing Q1-5, Q6 and Q10. I already have Q1 Uniform Acceleration done and over the past few weeks I've almost finished Q4 Pulleys and Wedges. Now I have 9 days left til 6th year and I was thinking of doing one more.

Initially I thought about doing Collisions (Chapters 6 and 7 in Murphy's new book?) but I don't think I'll get that finished in 9 days.

Can I finish Q2 Relative Velocity or Q3 Projectiles in 9 days if I work 2 hours a day?

Projectiles and Collisions are probably the easiest two Qs on the paper, you could definitely do one of them in 9 days, maybe even both! Never liked relative velocity myself. Don't count out hydrostatics, hardly anyone does it in the exam but many years its been extremely easy.

Peregrine

I'm looking through Projectiles and I see that you need to know Trigonometry. I'm still on JC trig, we won't be doing LC trig until December or something. Surely I can't manage without it?

I guess I'll do Impacts and Collisions.

decisions

Nimrod 7 wrote: »

I'm looking through Projectiles and I see that you need to know Trigonometry. I'm still on JC trig, we won't be doing LC trig until December or something. Surely I can't manage without it?

I guess I'll do Impacts and Collisions.

What do you need trig for?

Ompala

Nimrod 7 wrote: »

I'm looking through Projectiles and I see that you need to know Trigonometry. I'm still on JC trig, we won't be doing LC trig until December or something. Surely I can't manage without it?

I guess I'll do Impacts and Collisions.

Take a look at the trig first, its really just algebra at the end of the day re arranging things, you need it, albeit to a much lesser extent, for impacts and collisions too

Peregrine

decisions wrote: »

What do you need trig for?

I think it's mentioned as a requirement at the beginning of the Projectiles - inclined planes chapter and I looked through it and I don't understand any of it

Ompala wrote: »

Take a look at the trig first, its really just algebra at the end of the day re arranging things, you need it, albeit to a much lesser extent, for impacts and collisions too

Now I have a decision to make then.

2-3 hours a day, 7 days left, no LC trig. Projectiles or Collisions..


decisions, did you do Relative Velocity? Is it doable within that time?

decisions

For the inclined plane stuff all you need is to be able to resolve vectors. No complicated trig involved.

Personally I hate relative velocity, I never got it. Meaning if you need help I'm useless :P

Collisions is well do able in the timeframe you have, every single question you use the exact same basic method. (Up until my LC exam anyway)

Best of luck with it.