physics help needed........plz

[ashwinkandel]

The mass of a cube of aluminium is found to be 580 g with an uncertainty in the measurement of 10 g. Each side of the cube has a length of (6.0 ± 0.1) cm.
Calculate the density of aluminium with its uncertainty. Express your answer to an appropriate number of significant figures.

density= ......................±................... g cm-3

[elemis]

Whats the answer ?

[elemis]

^{equation 1}

adding the fractional uncertainties :^{equation 2}

Hence, multiplying 1 and 2 gives an absolute uncertainty of 0.2

Therefore, ans =

[Deadly_king]

The mass of a cube of aluminium is found to be 580 g with an uncertainty in the measurement of 10 g. Each side of the cube has a length of (6.0 ± 0.1) cm.
Calculate the density of aluminium with its uncertainty. Express your answer to an appropriate number of significant figures.

density= ......................±................... g cm-3

hey that's fro, June 09 p2, right??

Anyway it's not that difficult. Let me get this clear for you.

Density = Mass / Volume ---> density = 580/6³ = 2.685

Volume of cube = l³

Therefore density = m/l³

Delta D/density * 100 = delta m/mass *100 + 3deltaL/Length * 100

Delta D = [(10/580 * 100) + (3*0.1/6 *100) ] * 2.685/100 =0.18

Since all the values given were correct to 2 sf, your answer should be correct to 2sf.

Hence answer is 2.7  +- 0.2 gcm^-3

[elemis]

I got there before you

Good work man

[Deadly_king]

^{equation 1}

adding the fractional uncertainties :^{equation 2}

Hence, multiplying 1 and 2 gives an absolute uncertainty of 0.2

Therefore, ans =

Well done Ari.....except that the units are g/cm³

[elemis]

Well done Ari.....except that the units are g/cm³

I did that purposely because I wanted to see of you were paying attention

I was doing chem all this time..... concentrations and all

[Deadly_king]

I did that purposely because I wanted to see of you were paying attention

I was doing chem all this time..... concentrations and all

Haha........take it as if I believed ya

Yeah......i know you have loads on your head.....just chill and relax a bit dude

[ashwinkandel]

i looked up the marking scheme. it was given like this:
(answer 2.69 ± 0.09 g cm-3 scores 4 marks).
Can anyone teach me about the use of significant figures while solving the problems like the above one.

[Deadly_king]

i looked up the marking scheme. it was given like this:
(answer 2.69 ± 0.09 g cm-3 scores 4 marks).
Can anyone teach me about the use of significant figures while solving the problems like the above one.

Hmm.....this question carries 5 marks.

Ok........the values given to you and which you used in your calculations were 580g and 6.0cm.

In both cases the values were correct to 2 significant figures.

NOTE : The 0 in 580 is not considered as a significant figure but the one in 6.0 is considered as one. In decimals a zero in front of the other numbers is not considers as a significant figure (Example 2) but a zero after the decimal point which has a number in front is a significant figure.(Example 3)

Examples :
1. Express 5.89 correct to 2 sf ---> 5.9
2. Express 0.00875 correct to 2sf ---> 0.0086
3. Express 1.99 correct to 2 sf ---> 2.0

Hope it helps

[ashwinkandel]

thanks for the info. but i have one doubt. how many significant digits are there in the digit 1.001010. and how do we know how many significant figures should we use in the question i  asked.

[iluvme]

thanks for the info. but i have one doubt. how many significant digits are there in the digit 1.001010. and how do we know how many significant figures should we use in the question i  asked.

6 significant figures. You ignore the last 0.
Usually its to 3.

[Deadly_king]

6 significant figures. You ignore the last 0.
Usually its to 3.

Indeed it is 6

Good job girl
+rep

[iluvme]

Indeed it is 6

Good job girl
+rep

Thanks.
Isn't this like grade 5 math?
No offense meant to ashwinkandel.

[Deadly_king]

Thanks.
Isn't this like grade 5 math?
No offense meant to ashwinkandel.

Yeah......it's somehow similar though in physics it's much more complex