Help with Excel!!!!

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npanchal / GTP_N99GT
hi there folks....ive run into a slight problem with an assignment that ive got!!!

heres what the task is :




Now the bit that im getting stuck with is highlighted, where i enter that formula into excel and use it to work out the distances 'x'.

and this is what ive typed in as the formula BUT it give the wrong answer as i drag it down for other values of 't' (time)....



i think im getting it wrong to the part where i have to type in the values of (1-e^-kt)...and ive type dollar signs in so that i get the absolute cell references...

If anyone would know how to type the correct formula in i would be sooooooo grateful!! And if you need any other information drop a comment and ill get back!!


Thanks!
 
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You have k*2 instead of k^2 near the center of your formula.

You looked at that asterisk 147 times and saw a caret every time, didn't you?
 
You have k*2 instead of k^2 near the center of your formula.

You looked at that asterisk 147 times and saw a caret every time, didn't you?

ive changed it to ^2 but it still gives the same answser...
god i hate excel!!!:dunce:

to be honest i im being to see just a bunch of random letters and numbers!

EDIT - i think if i drag down the formula to the end it seems to 'look' right....But the great thing i asked my teacher to today and even they wernt too sure!
 
Hey, wait a minute. Now that I read the problem, rather than just compare the formula to your Excel formula, the formula is gibberish. The distance an accelerating object (with constant acceleration) travels is a function of acceleration and time, period. Mass has NO EFFECT on the distance!!!!

Constant acceleration is what gravity is, and we all know that gravity acts the same on a feather as it does on a hammer. They did it on the moon!

So their formula has nothing to do with what they're asking you to calculate.

Distance under contant acceleration is d=(1/2)at^2. End of story. (d is your x)
 
Hey, wait a minute. Now that I read the problem, rather than just compare the formula to your Excel formula, the formula is gibberish. The distance an accelerating object (with constant acceleration) travels is a function of acceleration and time, period. Mass has NO EFFECT on the distance!!!!

Constant acceleration is what gravity is, and we all know that gravity acts the same on a feather as it does on a hammer. They did it on the moon!

So their formula has nothing to do with what they're asking you to calculate.

Distance under contant acceleration is d=(1/2)at^2. End of story. (d is your x)

true, but i pointed a problem like this out to my teacher such as having '-' (minus) values for the distance such as -0.292!!!!

and the reply was and i quote 'i just a model so it may not work in practice', i think the point is that their just testing whether we are able to implement a formula into excel correctly even though the values may be bogus in real life if you catch my drift.....!

beside i think ive come across another problem with a different task....:grumpy:
 
No offence to you or your teachers, but only an idiot would use absolute cell references here.

This is what the Excel "define name" functionality is all about. So, you click on cell B1, and then click in the white box next to the formula bar (it shows the word "Sum" in your screenshot). Type in the word "acceleration".

Do similar, naming your variables in B2, B3 and B4 (e.g. "const", "drag", "mass","kval")

Then enter the formula using the names (Excel helps you by autocompleting them), thus:
=((acceleration*d2/kval)-acceleration/(kval*2))*1-exp(-kval*d2)

It's immediately more readable, plus you can move the parameter cells around - Excel will move their names with them.
 
No offence to you or your teachers, but only an idiot would use absolute cell references here.

This is what the Excel "define name" functionality is all about. So, you click on cell B1, and then click in the white box next to the formula bar (it shows the word "Sum" in your screenshot). Type in the word "acceleration".

Do similar, naming your variables in B2, B3 and B4 (e.g. "const", "drag", "mass","kval")

Then enter the formula using the names (Excel helps you by autocompleting them), thus:


It's immediately more readable, plus you can move the parameter cells around - Excel will move their names with them.


hmmmm.....didnt know you could write in formulas into excel like that!! but that what the task says....even though it does seem a little long winded.

beside ive come across this question which i dont really get...it might be quite simple but i cant seem to figure it out!

 
Well, you know m-zero from the first entry in the table. That leaves solving for a. But you don't know b[/I], so a will have to be given in terms of b. Now it's just goofy algebra. But it simplifies really quickly for t=0 . . . . . into something that makes no sense.

Wait. Is m-zero the mass at time zero (657,) or the empty mass (460?) If it's the empty mass, then a falls out very easily at time 0, because e goes away with a power of 0 (becomes a*1.)

Although one wonders what this car is powered by, if it burns 40 kilos of fuel in the first minute and only .3 kilos in the 19th.

I would suggest to your teachers, if I knew them, that matching problems to things that can actually happen rather than just throwing out fictional numbers to build worksheets from might make the problems easier to understand.
 
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Well, you know m-zero from the first entry in the table. That leaves solving for a. But you don't know b[/I], so a will have to be given in terms of b. Now it's just goofy algebra. But it simplifies really quickly for t=0 . . . . . into something that makes no sense.

Wait. Is m-zero the mass at time zero (657,) or the empty mass (460?) If it's the empty mass, then a falls out very easily at time 0, because e goes away with a power of 0 (becomes a*1.)

Although one wonders what this car is powered by, if it burns 40 kilos of fuel in the first minute and only .3 kilos in the 19th.

I would suggest to your teachers, if I knew them, that matching problems to things that can actually happen rather than just throwing out fictional numbers to build worksheets from might make the problems easier to understand.


lol i would to say that to my teachers but their the ones marking it!!!
turns out that the m0 and a are related to y=mx+c which can be attained by showing the equations on the chart in excel....Well that what i did anyways and its now all done and handed in!!! just 2 more assignments left until round 2!!!!

Thanks for the help people!!!! was very helpful!
:)
 
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