DCG~ Geologic Geometry

Paddy001

--paul-- wrote: »

What? if the gradient is 1 in 20 faliing then it will drop 5m if you go 100 metres down the road i.e 5 x 20=100? definitly not 10 m down if you go 100m down the road.

For mining geometry join the footwalls and headwalls in the elevation and go paralel to the footwalls from one of the headwalls and horizontally from the other headwall. this gives you a point on the strike, do the the same in the plan using the point you found on the strike, then look along the strike which gives you the dip and thckness.

Sorry your right, dunno what I was thinking!

Fince

Delta Kilo wrote: »

No it isnt but in fairness if you cant spot what is cut and what is fill then you shouldn't be doing DCG.

To confuse people further-does anybody use the "tadpoles" to indicate whether it is cut/fill. Remember, tadpoles always go UPstream.

so if ur cutting, the tadpoles are starting on the road side, and the sqiggle is going away from it and if ur filling the tadpole will be away from the road, with the sqiggle towards the road?

errlloyd

Fill has the tadpoles head right beside the road. Cut has the tadpoles tale beside the road.

KokaNoodles

Thanks all, but tbh im still a little confusd

Say for instance, B is at 55 and B to C is 1 in 20 falling

fill= 1in1.5
cut=1in1

How far out do i have to go? Dont know why i cant get this

Paddy001

KokaNoodles wrote: »

Thanks all, but tbh im still a little confusd

Say for instance, B is at 55 and B to C is 1 in 20 falling

fill= 1in1.5
cut=1in1

How far out do i have to go? Dont know why i cant get this

1 in 20 falling means when you go down 200m the road has fallen 10m. Therefore if you go down 100m it falls 5m, yes? Just go down as fas as you can and work out how much it has fallen then. You will only be ably to go down 100 most of the time. Next, at your new point draw your cone. If the whole thing is cutting just draw the one cone, cone will be radius 5 then as the cuttings is 1:1 and you have went down 5m so its 5mm cone. If you need to use an embankment cone, the ratio is 1:1.5 so the cone for this will be 7.5mm is that clearer?

Frolick

Any ideas what the short questions might be?

galway.gaa

Frolick wrote: »

Any ideas what the short questions might be?

i reckon well see skew lines, tangant planes?, solids in contact. there the 3 id go for if they were on

can anyone put up the list of possible qs they can ask on the short qs? that would be extremely helpful

Paddy001

galway.gaa wrote: »

i reckon well see skew lines, tangant planes?, solids in contact. there the 3 id go for if they were on

can anyone put up the list of possible qs they can ask on the short qs? that would be extremely helpful

short q's
skew lines
perspective
axonometric/dimetric/trimetric
ellipse/hyperbola/parabola
oblique planes

Long q's core
intersecting planes
interpenetration
conic sections (NB focal sphere)
oblique planes
axonometric/dimetric/trimetric
perspective

Frolick

axonometric/dimetric/trimetric
They came up in both sample and PRE paper so i would say it would come up in the short questions

Des23

The only paper that will have any bearing on what we get on Friday will be the official sample paper. That is the only one made by the SEC the others are made by companies. Axonmetric wasn't one of the long questions on that. I'm not saying that it won't come up, it obviously is a possibility, I'm just saying that you can't base predictions on the sample/pre papers. Which were in fact probably not made until after our paper was made.

Isaac702

Personally I dont mind what comes up with a few exceptions.
I dont want solids in contact or a long question on (Insert Topic involving parabola's (directrix, vertex, etc..) here)

Anything else would be easy enough to do.
An added bonus however would be if part a on the Structural Forms question didn't involve the hyperbolic parabola and just used a standard one.

timmywex

Right, my list of section a/b topics are as follows, anyone anything to add?

Planes/Dihedrel Angle
Skew lines
Oblique Planes
Interpenetration
Axonometric
Perspective
Solids In contact
Conics

croker1

personally i think if oblique planes and interpenetration dont come up as b's there will be uproar!!! all im hoping for is a nice interpenetration question and im sorted!:D

anyone doing the dynamic mechanism's question?? i find it fair hard! wat ye think of it???

Frolick

dynamic mechanism hmm...
Very long question, i'm staying well clear of it. Our teacher completely avoided it (aka we ran out of time haha)

-ilikeshorts

http://www.curriculumonline.ie/uploadedfiles/PDF/lc_dcg_sy.pdf

Thats the full curriculum theres a good bit there
Core: (A) Plane and Descriptive Geometry
Projection Systems

•Orthographic Projection
•Isometric drawing and axonometric projection
•Perspective drawing/projection
Plane Geometry

•Construction of Plane figures
•Construction of loci
•Circles in contact with points, lines and curves
Conic Sections

•Terminology
•Ellipse, Parabola and Hyperbola as section of cone and as geometric loci
•Tangency
•Derivation of focal points, directrix and eccentricity.
Descriptive Geometry of Lines and Planes

•Definition of plane, its true shape and inclinations
•Oblique and tangent planes; intersections
•Rectangular co-ordinates
•Skew lines
•Spatial relationship between lines and planes
Intersection and development of surfaces

•Surface development and envelopment of solids
•Intersection of surfaces; intersection of solids
Core: (B) Communication of Design and Computer Graphics
Graphics in Design and Communication

•Design strategies and design appraisal; the processes of design
•Generation and interpretation of design briefs
Communication of Design

•Drawing standards and conventions, presentation methods and layout
•Dimensioning and notation
Freehand Drawing

•Materials for freehand drawing
•Representing shape, form, texture and material; light and shade; use of colour
Information and Communication Technologies

•Graphics and CAD: terminology and software; sketching principles
•Presentation drawings, parametric models; use of templates and libraries
•Image processing and manipulation; data exchange; graphic output
Options: (Choose any 2)
Dynamic Mechanisms

•Involutes, helices and spirals and associated tangents
•Linkage mechanisms
•Cam profiles
Structural Forms

•Singly and doubly ruled surfaces, their projections and sections
•Translated surfaces; hyperbolic paraboloid
•Plane directors
•Geodesic Dome
Geologic Geometry

•Determining dip, strike, outcrop and thickness of strata; profiles from contours
•Use of skew boreholes
•Sections through strata
•Cutting and embankment sections for level and inclined constructions
Surface Geometry

•Development of surfaces, ducting and transition pieces
•Projection of transition pieces
Assemblies

•Interpretation of exploded and assembled drawings.
•Drawing layout and conventions; sectional views, hatching, dimensioning
•Machine surface and texture symbols; modelling assemblies

Des23

We did Geologic Geometry and Structural Forms, I don't know anything about the other questions but just from appearances I would think that these are the easiest two. There are very few new things to learn, just applying what you already know. Some of the structural forms part a questions in the sample papers can be done in five minutes, I just hope they are that easy on friday!

I've been doing old HL questions for the past few weeks, and realistically, while the drawing course is this year worth 60% rather than the 100% of old, it is definitely not true that we only have to know 60% of what they did last year. I would think that a lot of us would be able to answer both old papers fully and do well in the time that they were given. It is 4 questions isn't it?

I don't know what the solution is but it seems like we got a reasonably raw deal.

EDIT:
On consideration we probably wouldn't have much choice, but the point definitely still stands.

galway.gaa

croker1 wrote: »

personally i think if oblique planes and interpenetration dont come up as b's there will be uproar!!! all im hoping for is a nice interpenetration question and im sorted!:D

anyone doing the dynamic mechanism's question?? i find it fair hard! wat ye think of it???

ya were doin it. i think its 1 of the easiest qs. the book explains that section well and if you just work through some examples it can be a question where you can get the full marks