Homework Help

[StarsOfCCTV]

Solved the problem Luckily my mate was on msn..it was the way my teacher had written it he wasn't very clear

[StarsOfCCTV]

Help!

I'm doing coursework on grapes. I need to find out an alternative method for finding the concentration of sugar in the grape juice.

I know there is an experiment involving testing the amount of carbon dioxide given off...by the grape juice. I think that's the one I should do..

But I can't seem to find any information on the internet..

Anyone done or researched this before?

Thanks in advance

[Abigail]

The refractometer is precision laboratory equipment; or, more conveniently, it is a small hand-held device which can be used by the winemaker in the vineyard. The juice of a ripening grape is squeezed onto the device, which provides a sugar reading by the process of refraction. This process depends on how light changes direction when it passes between two media, in this case air and grape juice. The concentration of the solids in the juice affects the angle of change; measure the angle, and you have an indication of the concentration of the solids, which are mostly sugars.

A quite different method, however, is the hydrometer; this device is more likely (although certainly not exclusively) to be employed in the winery. The hydrometer is simply a hollow glass tube, bulbous and weighted at the bottom, so that it floats upright. As the concentration of solids in the grape juice affects its density, it will also affect how the hydrometer floats in the juice. The denser the juice, the higher the hydrometer floats; on the side of the stem is a scale, which allows the winemaker to make a reading. Just what the scale shows, however, depends on where he or she is working; there are many different scales for must weight.

Third paragraph under Must Weight http://www.thewinedoctor.com/author/sweetscience.shtml

This talks about making wine but apparently all wine makers need to know the concentration of sugars in the grapes before they start.

[StarsOfCCTV]

Thanks that was a big help

[ellis91]

OK, background. Its a while since I read this book and I didn't think it was worth all the hype. Anyway...

You're mean, I think it's the best book I've ever read.

[Abigail]

OK, background. Its a while since I read this book and I didn't think it was worth all the hype. Anyway...

You're mean, I think it's the best book I've ever read.

Nope, I couldn't get into it. Lots of waffle and thoroughly uninteresting.

[ellis91]

OK, background. Its a while since I read this book and I didn't think it was worth all the hype. Anyway...

You're mean, I think it's the best book I've ever read.

Nope, I couldn't get into it. Lots of waffle and thoroughly uninteresting.

I know what you mean I thought that when I started reading it the first time but after reading it again, I really got into it and I realized that the waffle was all there for a reason.

[ellis91]

I was wondering if anyone could help me with my maths revision.

I was looking through my quadratics revision notes and then I found that there was, what looked like a cubic equation; I’m guessing because one of the ‘n’s is to the power of 3.

I’m not sure how to solve it, would I factorise, because I’m assuming there’s 3 solutions since it’s cubic (I think).

Here’s the equation:

2n³ = 5n² + 3n

The problem I have is that I can’t factorise it into three binomials.

[Abigail]

Well... at the risk of sounding wrong I'd do:

2n^3 = 5n^2 + 3n

Always add the powers.

2n^3 = 5n^3 + 3

Add the numbers (I think)

2n^3 = 8n^3


Not sure where to go from there. I'd suggest 2/8, which would be 0.25. I think you subtract powers so it would just be 0.25n.

Its a long time since I did GCSE (I did higher but only did one year of it) so its a bit rusty. Does the question ask to solve the formula?

What exam board and course are you doing?

[di marco]

I was wondering if anyone could help me with my maths revision.

I was looking through my quadratics revision notes and then I found that there was, what looked like a cubic equation; I’m guessing because one of the ‘n’s is to the power of 3.

I’m not sure how to solve it, would I factorise, because I’m assuming there’s 3 solutions since it’s cubic (I think).

Here’s the equation:

2n³ = 5n² + 3n

The problem I have is that I can’t factorise it into three binomials.

wow its been a while since ive done this! yep youre right, cos its cubic there will be 3 values of n. start by making the equation equal 0 and then factorise it and in the bracket you should get a square equation (cant remember what thats called) and then work it out like normal. hope that makes sense, if you want any more help just ask