Engineering Marathon (2 Viewers)

[arman]

as if, i triple checked my answer and i'm 99.9999% sure it is right.

as if you can't find the length of the vertical member B, what? can't your teacher do simple trigonometry or similar triangles?

the length is not 1.7 .

i think he was pretty much saying it takes to long and is extremely unlikely to be asked to do something this hard in the exam,

and sorry if it seemed as though I thought ur answer was wrong, when i said close, i meant close to each other and so likely to be right

my answer is obviously wrong as the length is prob way out

 

[tommykins]

you wouldn't get that in a hsc exam i don't think, it requires too much of 3unit thinking to do so.

however, the solution is actually very simple and finding the height B isn't hard.

as i said, you can do it via similar triangles or trigonometry

 

[Kaos1]

the rotor blade of a helicopter is manufactured from a composite material.

give reasons for using a composite material in this application

 

[yz125]

the rotor blade of a helicopter is manufactured from a composite material.

give reasons for using a composite material in this application

composites are lightweight, have good resistance to cyclic stress and are also unaffected by the weather* (however can be degraded by UV rays), hence are suitable for a rotor blade.

question: Contrast the differences in transmission media (cable, microwave, fibre optics).

 

[arman]

question: Contrast the differences in transmission media (cable, microwave, fibre optics).

cable: multiple signals on one line but limited to a few hundred per line, needs boosting of electrical signal for long distances, speeds are restricted b y number of people on the line and distance to exchange. requires physical connection
microwave: can transmit long distances and through the atmosphere for satellite communication. wireless. requires direct line of sight
fibre optics: many thousands of signals can be transmitted by a single fibre optic. requires boosting of light wave for long distances. very fast speeds for broadband internet and multiple users but requires physical connection

 

[tashisthebest]

you see... i got .0014 aswell... but i went a totally different way...

please correct me where if i went wrong

E = FxL/Axe
(youngs modulas = (force x length) over (area x elongation)
therefore
2.1x10^8 = (1100 x 10) / (37^2 x e)
e = 1100 / (2.1x10^8 x 37^2)
= .0014

is that correct?

if ur using the length as 10 meters then shouldnt the area need to be converted into meters aswell and not milimeters??

 

[Kaos1]

. . . so the eqation should be

e = 11000 / (2.1x10^8 x 3.7^-3)

???

 

[Macdwg]

if ur using the length as 10 meters then shouldnt the area need to be converted into meters aswell and not milimeters??

What are you talking about, he used metres. The final answer is in metres.

 

[tashisthebest]

Kaos 1, im getting the same answer but i dont get, in your working out u had 37 squared, whats with that.
this is wat i did.

e= LF
EA
e= 10,000 x 1100
(210*10^9 x 37)

e= 1.415*10^-6mm

= 0.0014m

I just dont get that bit when u all of a sudden had 37 mm to the power of 2

 

[Kaos1]

i ... in the question, it said the area was 37^2 mm... i just plugged that into the equation

 

[arman]

Can someone please...

Briefly outline the different molding techniques for polymers

 

[Shepps]

Can someone please...

Briefly outline the different molding techniques for polymers

Types include: compression moulding, transfer moulding blow moulding, extrusion, blown film, thermoforming calandering (may not be the right spelling but what i mean is when the polymer is rolled), rotational moulding and injection moulding.

Note: I would go into detail probably a sentance on each, depending how much it was worth.

Question 2007 HSC Question 14 b: A high tensile steel pin with a cross sectional area of 110m2 holds a ram in place (as shown- picture irrelevant in maths). The ultimate shear stress is 880MPa and a factor of safety is 4 is to be used. What is the maximum shear force the pin can support?

 

[00iCon]

what about vacuum forming, the only one i know (other than injection moulding)

 

[bossleymaths]

Types include: compression moulding, transfer moulding blow moulding, extrusion, blown film, thermoforming calandering (may not be the right spelling but what i mean is when the polymer is rolled), rotational moulding and injection moulding.

Note: I would go into detail probably a sentance on each, depending how much it was worth.

Question 2007 HSC Question 14 b: A high tensile steel pin with a cross sectional area of 110m2 holds a ram in place (as shown- picture irrelevant in maths). The ultimate shear stress is 880MPa and a factor of safety is 4 is to be used. What is the maximum shear force the pin can support?

area = 110 * 10^-6
stress = 880 * 10^6
fos = 4
f=?

stress/ fos = force/ area

220 *10^6 = F /1.1*10^-4

force = 24200 N BUT THIS IS WITH U SAYING THAT PICTURE IS IRRELVANT

with picture then it would be 2 * 24200

=48400

 

[00iCon]

i ... in the question, it said the area was 37^2 mm... i just plugged that into the equation

37 mm² is 0.000037 m² not 1369 mm or whatever...

 

[tashisthebest]

i think we need a new question

How does a altimeter and airspeed indicator work?

 

[yz125]

i think we need a new question

How does a altimeter and airspeed indicator work?

Altimeter works on static pressure. As altitude increases, static pressure decreases, causing a diaphragm ( i think its a diaphragm) to expand. The expansion from the diaphragm acts on a linkage system which controls the needle on the altimeter, indicating the altitude.

Airspeed indicator uses a combination of static and dynamic pressure. This total pressure acts on a diaphragm, which is surrounded by static pressure. The diaphragm is connceted to a linkage system that controls the airspeed indicator. The variation in static and total pressure is an indication of the airspeed.

(Correct me if i'm wrong on any of this)

Question: Describe the nature and scope of a telecommunications engineering

 

[Kaos1]

a telecomunications engineer deals with all things to do with communication, fones, internet, wireless, cabels, all that, yeah yeah...

i need help on the '06 exam...

Q13, b, ii
a truck with a total hauling power of 400 kw is used to deliver precast panels to a construction site, the truck and trailer have a mass of 10 tonnes, and each pannel has a mass of 7.5 tonnes,

the truck is to climb a 100m long road with a grade of 1 in 5 (11.3 degrees), in 20 seconds, at a constant velocity.

calculate the number of panels the truck can carry. show all working (neglect the mass of the timber batterns and frictional rolling resistance.)


and question 14, a, ii
two lifting cabels, one on each side, are required to lift a 400kg door. the steel lifting cabels are each 5m long and each has a cross sectional area of 27mm^2. the modulas of elasticity of the steel in the cabels is 230GPa.

calculate the extension of each cable.

*i got 3.2mm each cable*

can someone plaese do these questions and tell me what they got?
include all working so we know how u got what u got

 

[arman]

Q13, b, ii
a truck with a total hauling power of 400 kw is used to deliver precast panels to a construction site, the truck and trailer have a mass of 10 tonnes, and each pannel has a mass of 7.5 tonnes,

the truck is to climb a 100m long road with a grade of 1 in 5 (11.3 degrees), in 20 seconds, at a constant velocity.

calculate the number of panels the truck can carry. show all working (neglect the mass of the timber batterns and frictional rolling resistance.)

\

P = W/t = 400kW

W = [delta]KE +[delta]PE = 400x10^3 * 20sec = 8x10^6 Joules

height = h = sin(11.3)*100 = 19.6m

since W = 1/2mv^2 + mgh = 1/2m*(100m/20s)^2 + m*9.8*19.6 = 8x10^6 J

therefore,

[edited:]

m*0.5*25 + m*9.8*19.6 = 8x10^6J

= m (12.5 + 192.08)

thus,

m = 8x10^6 / 204.58 = 39104.5 kg


39 tonnes - 10 tonnes = 29 tonnes

29 tonnes / 7.5 tonnes = 3.88 panels

therefore can carry 4 panels (rounding should be ok in exam???)

 

[Kaos1]

now that does make sense... i can see now what i wasnt doing...

i was trying to do it on the equation
P= (f x d) / t
power = (force x distance) / time

i didnt even consider the height, ke or pe...
woops

and the other question?