Comments on: Mrs Tibble’s Year 11 http://www.shsmaths.com Tue, 07 Feb 2012 21:11:26 +0000 hourly 1 http://wordpress.org/?v=3.0.4 By: Mrs Tibble http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9280 Mrs Tibble Tue, 07 Feb 2012 21:11:26 +0000 http://www.shsmaths.com/?page_id=1266#comment-9280 Hi Sophie, Sorry - only just seen this. It's the Fibonacci sequence. Mrs T Hi Sophie,

Sorry – only just seen this. It’s the Fibonacci sequence.

Mrs T

]]> By: Sophie Hart http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9279 Sophie Hart Tue, 07 Feb 2012 20:03:37 +0000 http://www.shsmaths.com/?page_id=1266#comment-9279 Hi Mrs Tibble I'm not sure what to do for exercise 20D question 5a? Hi Mrs Tibble I’m not sure what to do for exercise 20D question 5a?

]]> By: Mrs Tibble http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9220 Mrs Tibble Sun, 29 Jan 2012 18:56:14 +0000 http://www.shsmaths.com/?page_id=1266#comment-9220 Hi Ella, You need Pythagoras in the first triangle, which is what you did. (root 55) Next you need trig (SOH CAH TOA) for the right angled triangle in the middle. Lastly you need the cosine rule in the third triangle. Answers are 9.68cm and 13.1cm Hi Ella,

You need Pythagoras in the first triangle, which is what you did. (root 55)

Next you need trig (SOH CAH TOA) for the right angled triangle in the middle.

Lastly you need the cosine rule in the third triangle.

Answers are 9.68cm and 13.1cm

]]> By: Ella Castle http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9218 Ella Castle Sun, 29 Jan 2012 18:45:04 +0000 http://www.shsmaths.com/?page_id=1266#comment-9218 Hello sorry for the question that you set us from the exam, I'm finding it really difficult to figure out (b) of the question. I found the side of CD using pythagorus and got the answer 11.1cm but now I'm beginning to doubt that because I can't find the other side. How do I find the other side? Thank you Hello sorry for the question that you set us from the exam, I’m finding it really difficult to figure out (b) of the question. I found the side of CD using pythagorus and got the answer 11.1cm but now I’m beginning to doubt that because I can’t find the other side. How do I find the other side? Thank you

]]> By: Mrs Tibble http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9131 Mrs Tibble Sat, 31 Dec 2011 17:32:59 +0000 http://www.shsmaths.com/?page_id=1266#comment-9131 Hi Zoe, The difference with direct proportion is that you divide to get the constant. Mrs T Hi Zoe,

The difference with direct proportion is that you divide to get the constant.

Mrs T

]]> By: Zoe Wells http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9130 Zoe Wells Sat, 31 Dec 2011 17:19:42 +0000 http://www.shsmaths.com/?page_id=1266#comment-9130 Yes great, thank you! Yes great, thank you!

]]> By: Mrs Tibble http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9129 Mrs Tibble Sat, 31 Dec 2011 17:07:48 +0000 http://www.shsmaths.com/?page_id=1266#comment-9129 Hi Zoe, Q. The pressure of a gas P is inversely proportional to its volume V. V is 10 litres when the pressure is 4 atmospheres. a) what is the pressure when the volume is 8 litres? b) what is the volume when the pressure is 2.5 atmospheres? Answer: P is inversely proportional to V so PV=k From info at start, k = 10 x 4 = 40 (note: the units don't matter so long as they are always the same in each part of the question) Now you know the constant is 40 so every pair of values must multiply to 40. a) P x 8 = 40 therefore P = 40/8 = 5 litres b) 2.5 x V = 40 therefore V = 40/2.5 = 16 atmospheres Does that help? Mrs T Hi Zoe,

Q. The pressure of a gas P is inversely proportional to its volume V. V is 10 litres when the pressure is 4 atmospheres.

a) what is the pressure when the volume is 8 litres?
b) what is the volume when the pressure is 2.5 atmospheres?

Answer:
P is inversely proportional to V so PV=k

From info at start, k = 10 x 4 = 40 (note: the units don’t matter so long as they are always the same in each part of the question)

Now you know the constant is 40 so every pair of values must multiply to 40.
a) P x 8 = 40 therefore P = 40/8 = 5 litres

b) 2.5 x V = 40 therefore V = 40/2.5 = 16 atmospheres

Does that help?

Mrs T

]]> By: Zoe Wells http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9128 Zoe Wells Sat, 31 Dec 2011 16:39:51 +0000 http://www.shsmaths.com/?page_id=1266#comment-9128 Thank you very much. Could u possibly type out a question and a solution? So i can see the step by step method? Thank you very much. Could u possibly type out a question and a solution? So i can see the step by step method?

]]> By: Mrs Tibble http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-5/#comment-9123 Mrs Tibble Fri, 30 Dec 2011 16:09:52 +0000 http://www.shsmaths.com/?page_id=1266#comment-9123 Hi Zoe, For inverse proportion, the product is constant eg if P is inversely proportional to V, then P x V = k (the constant of proportionality) so every pair of P and V values will multiply to give you that same answer (k) If there are powers, then remember to apply them: eg A is inversely proportional to B-squared then A x B-squared gives you the constant, not A x B With this one, if you have to find B, then the proportionality will give you B-squared and you need to remember to square root it at the end. Try here for some practice questions: http://www.mathsmadeeasy.co.uk/GCSE-maths-revision/prop-inverse/direct-inverse-proportions.htm Have fun ;-) Mrs T Hi Zoe,

For inverse proportion, the product is constant

eg if P is inversely proportional to V, then P x V = k (the constant of proportionality)

so every pair of P and V values will multiply to give you that same answer (k)

If there are powers, then remember to apply them:
eg A is inversely proportional to B-squared
then A x B-squared gives you the constant, not A x B

With this one, if you have to find B, then the proportionality will give you B-squared and you need to remember to square root it at the end.

Try here for some practice questions:
http://www.mathsmadeeasy.co.uk/GCSE-maths-revision/prop-inverse/direct-inverse-proportions.htm

Have fun ;-)
Mrs T

]]> By: Zoe Wells http://www.shsmaths.com/get-help/year-11/mrs-tibble/comment-page-4/#comment-9122 Zoe Wells Fri, 30 Dec 2011 15:11:24 +0000 http://www.shsmaths.com/?page_id=1266#comment-9122 Hi Mrs Tibble, I was doing inverse proportion and i looked at my notes but i don't understand them, could u please possibly tell me a website i could go on to explain to me how to do it!? Hi Mrs Tibble, I was doing inverse proportion and i looked at my notes but i don’t understand them, could u please possibly tell me a website i could go on to explain to me how to do it!?

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