Engineering Thread

TheAmateur

devinejay wrote: »

Meant to say, anyone else attend that chemistry tutorial yesterday? Lucky for those who stayed away!

What a waste.

Baza210 wrote:

Some kindly soul please explain how to do this. D is the correct answer, apparently.

We did one kinda like this in a tutorial, with three people lifting a table. You'll have three equations: sum of vertical forces =0, moments about A (or B or C your choice) on the "x" axis = 0 and moments about same on the "y" axis = 0. hard part is figuring out the distance from b and c to a or whatever on the x and y axis. Think that's it anyways. Did anyone get the "power developed in a car travelling up a hill" question on that paper. It's Q. 31.

devinejay

Sure was a waste, reminded me sooo much of his lectures, so instead of helping me catch up on what I haven't learned, it just reminded me why I never learned it in the first place.

Oh and ignore my way of doing it, too complicated. Like TheAmateur says, look at it horizontally and nobody cares if it's a circle, it's just like the table question then.

Brian

Q31 looks like kinetic + potential energy to me.

Brian

Why is google calculator saying sin 7 = 0.657

devinejay

Baza210 wrote: »

Why is google calculator saying sin 7 = 0.657

Radians

Brian

Bwahahaha, got 31 out.

Kinetic energy is constant. Potential is increasing.

100 km/hr * 5/18 = 27.8 m/s

27.8 sin 7 = 3.39 - car is rising at 3.39 m/s

increase Ep/s = mgh = 2000 * 9.81 * 3.39 /s
= 66.5 kW

Engine at 65% efficiency

66.5/0.65 = 102kW, answer B.

devinejay

Did we maybe do this in a lecture, haven't a clue how to do it.

Brian

No idea. I would've guessed A since it's a triangle, and its CofG is lower, but no idea about the numbers.

Jonathan

Baza210 wrote: »

Why is google calculator saying sin 7 = 0.657

n00b

devinejay

I guess that's the beauty of MCQs

TheAmateur

devinejay wrote: »

Did we maybe do this in a lecture, haven't a clue how to do it.

yep we did that in a lecture. should be with your notes from Dr. O Dwyer.

Baza210 wrote: »

Bwahahaha, got 31 out.

Kinetic energy is constant. Potential is increasing.

100 km/hr * 5/18 = 27.8 m/s

27.8 sin 7 = 3.39 - car is rising at 3.39 m/s

increase Ep/s = mgh = 2000 * 9.81 * 3.39 /s
= 66.5 kW

Engine at 65% efficiency

66.5/0.65 = 102kW, answer B.

Yep that's the right answer anyways... Howcome the only work done is to raise the car though? Where I went wrong was adding the kinetic energy...

Brian

Great. That probably means every single question I've ever done with Google Calculator was wrong. I hate rads.

devinejay

notes from Dr. O Dywer, where did I put them.....?

Oh now I remember, that man put me to sleep so much it was like I had note-taking triggered narcolepsy, that's that then!

TheAmateur

devinejay wrote: »

notes from Dr. O Dywer, where did I put them.....?

Oh now I remember, that man put me to sleep so much it was like I had note-taking triggered narcolepsy, that's that then!

These aren't great notes, but they might convey the idea.

Brian

You're only trying to find the energy used at that time. The car's not accelerating, so the kinetic energy is constant which means it's not using any of the energy developed by the engine.

Brian

Nice try :P

Brian

I thought O'Dwyer was a good lecturer, actually. One of the best we had.

TheAmateur

Baza210 wrote: »

You're only trying to find the energy used at that time. The car's not accelerating, so the kinetic energy is constant which means it's not using any of the energy developed by the engine.

Makes sense now. Thanks man!

devinejay

Thanks TheAmateur.

I don't think he was a bad lecturer, but the subject matter was generally hard to get excited about. Plus there was always a hum of chatter in his lectures that you had to strain to listen over which didn't help.

Brian

Y'all see the article on the Six One news?

http://dynamic.rte.ie/av/230-2544206-320-180.smil

devinejay

Enlightenment please.

Also wtf is a .smil?

Jonathan

Baza210 wrote: »

Y'all see the article on the Six One news?

http://dynamic.rte.ie/av/230-2544206-320-180.smil

My gmail account can only be reset using my TCD one, which can only be reset by knowing my college credentials which expire every 180 days.

Fcuk you hackers.

Jonathan

devinejay wrote: »

Enlightenment please.

Also wtf is a .smil?

Real(ly sh1t) Player playlist.

TheAmateur

Baza210 wrote: »

Y'all see the article on the Six One news?

http://dynamic.rte.ie/av/230-2544206-320-180.smil

WTH?!? RTE have a computer?!?

Jonathan

TheAmateur wrote: »

WTH?!? RTE have a computer?!?

Get with the times sonny..

http://www.rte.ie/player/

Brian

RTE did a bad job of editing that video. You can see the url of the website in question in his google cache request. But the page is in Arabic. Haven't been able to find anything in it - looking through cache'd pages is tough.

Brian

Found the URL of the thread with all the passwords in it, but it's been disappeared, along with Google's cache of the page (though the page is still returned in Google results)

Brian

http://innealtoir.com/baza210/1e6_defs.zip

Jonathan

Baza210 wrote: »

http://innealtoir.com/baza210/1e6_defs.zip

Phone is telling me zip is corrupt.

This the doc with all PF's definitions?

Brian

Yes. The ZIP is not corrupt, your phone is.