Engineering Maths Help! Moments?

[bikertomm]

Hi lads,

I'm struggling with this question quite a lot.

I think on one hand it may be relatively simple and I am missing the point completely.

But really I have no idea what I'm doing and can't find any decent information online.. The tutor isn't much good either

Here is the question:

https://i1145.photobucket.com/albums/o520/bikerrtomm/20140429_214655_zpsa383087c.jpg

Now, the principle of moments is when forces produce a turning effect, it can be measured by the product ( W x A ) where W is the force and A is the perpendicular distance between the pivot and the line of the force.

The product is called the turning moment of the force.

Does the weight acting at the centre have anything to do with it? Would that make it W x 0.5m = ?

I'm very lost, and got the answer of 50 Newton Metres by messing about.

If anyone has any ideas I'd be very appreciative.

Cheers!
Tom
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[Lord Percy]

I think the bit that's puzzling you most is how the weight of the box is acting and contributing to the overall moment.

It acts from the middle of the box. So you can essentially ignore the whole box and re-draw it as shown in the image below.

Find x with pythagoras, convert the 100kg to Newtons, then resolve the force into its perpendicular components with a bit of trigonometry and work out the overall moment of the box in that position.

The rest you should be fine with. If not I'll draw a more detailed diagram

https://i62.tinypic.com/2url2r7.jpg

[Gazza M]

Not quite Percy:

Moment = force x perpendicular distance

So take moments about point C
https://i1125.photobucket.com/albums/l598/gazzam1/20140429_231321_zps7e1898a2.jpg
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[Lord Percy]

[Gazza M]

[Clarkie]

I approached it by taking the mass of the block as a uniform distributed load across the horozontal metre giving ~490N force on the top centre of the block so using this you'd only need 490N of force at a distance of 1 metre from the ground to lift point B.

Hope that makes sense?

[bikertomm]

Right, thanks very much for the replies lads.

Makes a bit more sense, but going to need a whole lot more practice on that..

Serious

Tom
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07' Honda Hornet now full powaah! My guide on performing an oil change!

[mentalboy]

How old are you lot?

This was 'O' level syllabus standard - taken before you hit 17!!!

Please, please don't say this is for a university degree.
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[Lord Percy]

I did it at 'A-level' first-year standard. Which is usually done by 17 year olds.

I was 24 though

[dydey90]

I did this at the start of my HNC about 18 months ago and I can't remember a damn thing about it!

Just wait until you get onto the maths behind proving thermodynamic equations...
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[Gazza M]

Can't remember when I first did it, a while back... I'm in my 3rd year of a mech eng degree so this is bread and butter stuff really.
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Present: '05 R6 track bike, 140 pit bike

[Nick 50]

[bikertomm]

I'm 20 and in the first year of a HNC mech design.

Funding it myself, and getting royally fucked over in maths, finding it really tough.

Will have to have a big fuck off revise through the summer or I won't pass the exams. Everything else has been fine up to now though, the CAD & other lessons. Just maths killing me.

and Edit: Reason I had no clue with this is that we haven't been taught it.. and I couldn't find anything online that made sense.

Cheers again
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07' Honda Hornet now full powaah! My guide on performing an oil change!

[clancy]

I'm in my 3rd year of civil engineering, we have some shit hot lecturers and im pretty sure there is some really well explained basic stuff on my portal somewhere. If I can find it ill stick it up for you
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KLX 300r

[bikertomm]

[Gazza M]

[clancy]

Gazza, you gonna apply with the other 10k mechanical graduates ? everyone of them I've met only wants to work in f1
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KLX 300r

[Nick 50]

[Nick 50]

[clancy]

That's cool nick, I know a lad who went into nuclear engineering, not consultancy as such though. We live next to one of the biggest dockyards in the country, the navy have their nuclear submarine refit centre there. So he works on refitting them, it's pretty cool

With a bit of luck I'll be working in there too soon, doing refits amongst other bits and bobs
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KLX 300r

[Lord Percy]

I intend to maybe worm my way into nuclear energy. Gonna possibly have to retrain a little though as my degree is in physics so I may need to shift away from the in-depth theory stuff and teach myself the engineery bits. Early days yet though.

[bikertomm]

My tutors just said the answer is 9810? Mind blown
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07' Honda Hornet now full powaah! My guide on performing an oil change!

[trevor saxe-coburg-gotha]

There was a time when Derivative would come on here and totally own a thread like this. God knows what happened to him.
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Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[Scythe]

[Gazza M]