expotential growth

[mollykins]

do these numbers correlate with expotential growth? remembering that that don't all go up in even intervals?

concentration . . . ml/s
0.2...............0.05 cm /s
0.6............0.165 cm /s
0.8..............0.27 cm /s
1...............0.535 cm /s
2...............3.275 cm /s


if it wasn't, half way between the 0.2 and 0.6 reading would be 0.1 and then 0.8 would have to be something like 0.2 and 1 would be about 0.25 wouldn't it?

[jno]

do you mean 'exponential'?

Some proper scientist could probably put me right.

Sorry, don't know the answer.

[bibblebub]

take logs and see if you have a straight line graph

[mollykins]

yes, exponential.

do you mean logorhythms? i havent done them but i probably have. i mean i havent been taught them, but i plotted them in a graph , but only up to 1 molar concentration is in proportion, but they don't make a straight line
.

[mollykins]

and i extended the line, in my head with the ruler and where two would be if it were in proportion, isn't where it is, if that makes sense.

[dr b]

is this just a yes or no question, or are you being asked to actually estimate what the relationship is?

[bibblebub]

if x = a.y^n

then taking logs (any base , 10 or natural or whatever) gives

log(x) = n.log(y) + log(a)

i.e. plotting log(x) against log(y) is a straight line

if not exponential then won't be a straight line

[bibblebub]

p.s. usually you would use the x and y the other way round i.e. y = a.x^n

[factor-fiction]

logorhythms? Are they like biorhythms?
What are you units- they look like centimetres per second which is velocity not concentration.
If you put your data into a spreadsheet and do a scatter graph you'll get curve which gets progressively steeper. Try it and see

[mollykins]

logorithms, i never done them.

i did have 0.4 but that measurement was wrong, so i'm left with these. i think i should mention if the values would go up in a straight line, or if not, whether it is exponential growth.

[dundurn]

If you have MS Excel then put your values into a two column table and then graph them as an XY graph. You can then add a trendline. Exponential looks about right. I reckon your .4 value would have to be about 0.0825 to keep the curve unchanged.

[mollykins]

i handed it in and the teacher said that it looked about right. thanks for your help guys.