Level Heading
Questions and Answers
These are some of the questions ... and answers that I've provided so far.
Chenea asked
I have a question about science and I was wondering if you could possibly help out. It concerns the conductors of electricity. My friend and I were discussing with our teacher whether gases could be conductors of electricity. Could you possibly help me?
I am in grade 9 and am 14 but the answer may need to go to a higher level and I believe that I will be able to understand answers at a higher level because I have a good understanding of scientific concepts. Anyway if you could help out in anyway and maybe give an example of a case where gas could be a conductor then that'd be great.
Answer
Gases conduct electricity - it's just that they don't do it very well. That's why you usually need very high voltages to get it going.
So - static zap - is felt and sometimes heard because of the high voltage which zips through the gas. Same with lightning - an extemely high voltage causes the air to ionise enabling the gas (air) to conduct. Then fluoresecnt lights have a starter in them. This boosts the voltage to a high enough size to ionise the mercury vapour in the tube. Then the gas (mercury vapour) conducts electricity. So ... if electricity can pass through it - then the gas is conducting.
As for conducting like a metal - nope - it's not that good.
Geri asked
I'm a Year 10 student from Melbourne, Australia. I have a question for you...
"You have attended a formal function and are introduced to four people: Jim, Isabelle, Darcy and Karen. Each of you shook hands with one another. Isabelle commented on the large number of handshakes that occured. She said, I wonder how many handshakes would take place if there were 100 people? Jim said, simple, twenty times the amount of handshakes that took place between us five.
Was Jim's statement correct?" 1. How many handshakes took place with five people? 2. If we double the size of the group to ten people, will the number of handshakes double? (personaly I don't think so) 3. You are to work out a method for calculating the number of handshakes needed for ANY number of people to introduce themselves (explain why it works out)
Answer
This sort of question is best answered by trying to see a pattern ... if you can work out the pattern then you can work the answer for any number.
Start with small numbers because they're easy to work out ...
how many handshakes between:
No of People No of Handshakes
2 1
3 3
4 6
5 10
You might be able to see a pattern forming - look at the differences between the number of the handshakes:
No of people No of handshakes Difference
2 1
3 3 2
4 6 3
5 10 4
6 __ 5
7 __ 6
and so on.
OK now there's a pattern how do you work out the total number of handshakes for let's say 10 people?
According to the pattern that would be
1 + 2 + 3 + 4 + 5 + 6 .... + 9
Personally, I don't like adding up odd sets of numbers so, lets add in another 10 to make it an even set of numbers to work on. Then when we get the answer we'll have to remember to take off that 10. I know it adds another step, but it will be easier in the long run.
So, how do you quickly add ten consecutive numbers?
add the first and last numbers 1 + 10 = 11
then second and second last 2 + 9 = 11
then third and third last 3 + 8 = 11
then the fourth and fourth last 4 + 7 = 11
then fifth and fifth last 5 + 6 = 11
__________________
5 times 11 = 55
Take off the ten we added in = 45
Let's try it with 20 people.
That will be 1 + 2 + 3 + 4 + ... + 19 handshakes
Add 20 to make an even set of numbers ...
1 + 2 + 3 + 4 + ... + 19 + 20
Add the first and last = 1 + 20 = 21
How many times will you do this ? 10 times because there are 10 pairs of numbers.
So 10 times 21 = 210
Take off the twenty we added in = 190
Do you get the idea?
So, what's the answer for the number of handshakes among 100 people?
Jeff asked
Please could you tell me the answer to the following: 30p:£2 using the form of 1:n. I really need to know it by tonight, no later than 19:15
Answer
I'm in Australia (the state called Tasmania - the island hanging off the south bit) and we don't use pounds any more. We used to but we stopped in 1966. Still there's a hundred cents in our dollar. A hundred pence in your pounds. So, the answer will still be the same.
One possible answer using decimals ...
How many 30p's in $2?
Change the $2 to p's = 200p and
divide by 30 = 6.67
So ratio is 1 is to 6.67
Another using fractions
Instead of 6.67 use 6 2/3 (six and two thirds)
You can then say your answer is 1 is to 6 2/3 or 1 is to 8/3 (eight thirds)
But this looks messy - so multiply everything by three to get rid of the fraction bit ... Now it's 3 is to 8
This is a better way to write the answer, but if it has to be a 1 on the left hand side then any of the above answers is right (I hope).
Geri asked
Could you please tell me what a diagonal is? I presume it is a line spanning from one corner to another, eg, with a square, a line spans from the top left, to the bottom right, and another from the top right, to the bottom left, so there forms a cross :)
Also, how can I work out a rule to work out how the number of sides of a polygon shape, relates to the number of diagonals that can be drawn
Your help would be much appreciated.
Answer
I will assume that you are talking about regular polygons like a square, pentagon, hexagon and so on ... otherwise it's much, much more complicated.
Like your last question, this one works on patterns.
Number of sides Number of diagonals Difference
3 0
4 2 2
5 5 3
6 9 4
7 14 5
(Draw a quick picture to check it)
There's a lot more maths involved in this but you can investigate the rest. Remember - look for patterns.
Here's one pattern you might have already seen 1 2 3 5 8 13 21 ... what's next?
Adela asked
I really need information on the phi function. I am in Year 11 and doing London Mathmatics G.C.S.E higher level coursework. I especially need to know about how the phi function, indices and prime numbers are linked (via equations etc) I need help A.S.A.P. Sorry it is a bit vague Thank you.
Answer
I provided Adela with some resources available on the Internet.
Jenni asked
This is for Biology and I'm in 9th grade
How dose codon differ from a DNA triplet?
How does anticodon differ from a DNA triplet?
Name three types of DNA - explain the function of each type.
I need this at about 9:00pm tonight 1-03-00 thank you.
Answer
Firstly, a DNA molecule is a very large molecule made from many smaller components. The most important of these are the four bases (Thymine, Adenine, Cytosine and Guanine).
The shape of the DNA molecule is like a coiled spring (this shape is called a helix and not a spiral). The clever bit is that the DNA molecule is actually two long springs twined around each other. They are held together by the bases locking together in pairs (like fancy lego). The pairs are always Adenine and Thymine, Cytosine and Guanine.
And just to make things a little more difficult, the four bases in RNA are Adenine, Cytosine, Guanine and Uracil (you'd better check the spelling). Each group of three bases is called a codon because it's genetic code for one amino acid.
The aim of the whole process is to produce proteins, but it's all done in a very indirect way. The DNA is the master tape and from it is produced RNA (ribose nucleic acid) of a type called messenger RNA. The mRNA has the codons.
Elsewhere in the cell there is another type of RNA called transfer RNA. At one end of the tRNA there is a group of three bases - the anti-codons and at the other end, a particular type of amino acid. Each group of three bases on the mRNA is able to match to a group of three bases on the tRNA.
In the cell there are special structures called ribosomes that can move along the mRNA molecule and 'read' it like an audio tape. The ribosome provides a place where the mRNA and tRNA are able to click together and bring the amino acid into position. The ribosome moves into the next position to read the next codon, the next amino acid moves in and gradually a chain of amino acids builds up - the chain of amino acids is called a protein.
======================================================
Here is a definition I got off the net:
Codon
A sequence of three consecutive nucleotides in a DNA or RNA molecule that codes for 1 of the 20 amino acids in proteins or for a signal to start or stop protein production.
http://www.nih.gov/nigms/news/science_ed/definitn/codon.html
This looks like a good site to learn exactly what's going on ...
http://www.sciences.sdsu.edu/Faculty/Paul.Paolini/ppp/lecture8/sld001.htm