Tech Graph Paper 1 Thoughts.

emptyspoon

fivetwenty wrote: »

Hang on - is this the wrong idea then?

I got a parallel line in Drawing one with the horizontal axis below it, with the distance being 54? What was the way you did it?

If the line was parallel to the horizontal plane, the xy plane, in the original elevation (drawing one?) then that's right. And the distance from that to the horizontal plane, you just measure up from the xy plane to it. Hmm.. if you got 54, then one of us has made a mistake!

emptyspoon

fivetwenty wrote: »

I find it hard to believe that people got 74mm altitude given that lACl only reached 70mm altitude? Therefore the line couldn't possibly connect?

AC goes up to 95 altitude. C is at up 95, A was at 30 or something.

life_is_music

fivetwenty wrote: »

Yeah, and I did mark the height and got 54mm between the lines.

I find it hard to believe that people got 74mm altitude given that lACl only reached 70mm altitude? Therefore the line couldn't possibly connect?

The height of C is 95 mm and F is 80mm so it is possible.

Maybe it has something to do with the use of Datum lines???

fivetwenty

Ok then - time to drop TG1 for the weekend, although I'm more unsure now than I was when leaving!

Decerto

all the people who got 54mm, do yous know the difference between shortest horizontal distance and shortest distance?

turgon

Ok these post mortoms are annoying!!!!

Wait 'til August, your just freaking out everyone, including me!!

cHaTbOx

turgon wrote: »

Ok these post mortoms are annoying!!!!

Wait 'til August, your just freaking out everyone, including me!!

+1

Not going to help anyone

ZorbaTehZ

I didn't sit the paper, but looking at it on examinations.ie it seems about ok, not too easy or too hard. Q5b I'd say would probably have put quite a few people off, Q1c was very nice though, Q7 inclination of the cut surface is a nasty thing too ask too. On question 1D all you had to do was measure from the line to x1y1 for the answer (if you had done shortest distance, instead of shortest horizontal distance, then you wouldn't have been able to do this).

declan_lgs

Just to clarify for paper 2, if you do the same Q twice, you get the marks for your best attempt right?

Also, if you mess up the road geometry the superintendent will have extra sheets for you right?

4dsnare

fivetwenty wrote: »

Yeah, and I did mark the height and got 54mm between the lines.

I find it hard to believe that people got 74mm altitude given that lACl only reached 70mm altitude? Therefore the line couldn't possibly connect?

q1 (d)the line ac went higher than 70mm, i got 75(well 74.5 but i rounded it up cos i taut 75 sounded more right!) I didnt bother measuring dihedral angle but know i got it right and for part c the angle is 75 or 15 depending on what way you measured it

q2 (a) and (b) very easy and i tried diferent locuses for c but they just wudnt work for me so i dont think ill be counting this q

q3 so easy got it done in 15 mins, no tricky part at all as long as you know to put the sphere and the inverted cone into to 75dgre cones

q4 looked easy because barely any turning points but the bottom of it had alot of hidden detail, fairly sure i got it right because wed done 1 like it in class and our teacha told us to look out for d detail, garantee it cot alot of ppl out

q7 (a) and (b)part1 were easy but i measured the angle usin the wrong veiw, i think it shud av worked out around 60 bu i got lik 47, part(c) had me thinking for awhile but it was easy in the end.

I taut it was a fair enuf ppr, pretty confident of all my answers cept 4 q7(b)part2 but i wont loose much for that, hopeing for an a1 since i got one in the pre!!!!!

q

sd123

ZorbaTehZ wrote: »

I didn't sit the paper, but looking at it on examinations.ie it seems about ok, not too easy or too hard. Q5b I'd say would probably have put quite a few people off, Q1c was very nice though, Q7 inclination of the cut surface is a nasty thing too ask too. On question 1D all you had to do was measure from the line to x1y1 for the answer (if you had done shortest distance, instead of shortest horizontal distance, then you wouldn't have been able to do this).

+1. I only covered 4 questions on each paper for my LC but fwiw, the ones I covered were very acceptable on this years paper (1,3,5,7), although 7 was fairly long, and tedious. I can't talk bout the others, unfortunately!

declan_lgs wrote: »

Just to clarify for paper 2, if you do the same Q twice, you get the marks for your best attempt right?

almost definitely, although theres no point in starting again from scratch, unless you make an absolute balls of it, and have loads of time. Chances are neither will be true!

Also, if you mess up the road geometry the superintendent will have extra sheets for you right?

Maybe, there's one map in each paper, so if there's loads of extra papers, there'll be loads of extra maps. In my school last year, there was about 5 extra, and 2 people made mistakes, and had to get new ones. Don't assume that there'll be another one for you!

Decerto

Reason why some people are getting 54 and others are getting 74 is that some people when they brought their shortest h. distance back to first elevation measured from there to they xy line and got 74 and others measured it from the auxillary elevation to x1,y1 and got 54

shortys94

How did you get the side of the square in Q.7?

life_is_music

draw in the length of the side in the auxiliary (along your trace).
Then swing an arc of 85mm from O and come tangental to it from H1T1.

shanedownfall

This has being annoying me!... How the hell do ye find the second focal point of part B Q6?!

Was really pissed off with this question. Have been able to do every conics question for the last 10 years, but not this one!

yenoolnairb

I got 75mm (74.5) in 1 (d). I thought the paper wasn't that bad overall. In question 3 (b) how were you supposed to know the height of the cylinder? i just did some educated guessing slyly

Dr.Millah

yenoolnairb wrote: »

I got 75mm (74.5) in 1 (d). I thought the paper wasn't that bad overall. In question 3 (b) how were you supposed to know the height of the cylinder? i just did some educated guessing slyly

It wasnt until i left the exam that i noticed a small line extending from the side of the sphere which gives the height. i guessed aswell.

fivetwenty

shanedownfall wrote: »

This has being annoying me!... How the hell do ye find the second focal point of part B Q6?!

"B" was a vertex, then bring F perpindicular to the other tangent, where it touches that tangent - join that point to B, bisect it and the perpindicular bisector bisects the axis at the centrepoint of the Ellipse.

I couldn't determine the Directrix having drawn the bloody Ellipse! It was probably easy but I just blanked

shanedownfall

Thanks for that. Can't really understand the principle behind this though. Never came across a method like it before. Is it going back to junior cert tangent methods?

Getting the line of eccentricity is easy enough once you have the curve. Pick a random point (p), and work backwords using the method you would have used to find the point if you already had the eccentricity line.
ie. from the focal point swing an arc from p back to hit the focal line. Where it hits the line, draw a line perpindicular to this point, and one straight up from p. Where these intersect is a point on the line of eccentricity. I think you'd have do this with two pts to know what angle it is.

starkinter

shanedownfall wrote: »

Thanks for that. Can't really understand the principle behind this though. Never came across a method like it before. Is it going back to junior cert tangent methods?

You could also use this method:
Tangents from the same point are equally inclined to the focal points.

fivetwenty

Interesting - but the Directrix?

fivetwenty

shanedownfall wrote: »

Thanks for that. Can't really understand the principle behind this though. Never came across a method like it before. Is it going back to junior cert tangent methods?

Getting the line of eccentricity is easy enough once you have the curve. Pick a random point (p), and work backwords using the method you would have used to find the point if you already had the eccentricity line.
ie. from the focal point swing an arc from p back to hit the focal line. Where it hits the line, draw a line perpindicular to this point, and one straight up from p. Where these intersect is a point on the line of eccentricity. I think you'd have do this with two pts to know what angle it is.

Oh sorry - missed your answer!

And my principle was the fact that focal points meet a tangent at points on the major axis circle.