Question

The density of cylindrical rod was measured by
ρ =4m/ ПD2l

The percentage error in m, D, l are 1%, 1.% and 0.5%. Calculate % error in the
calculated value of density.

Answer 1

\[\frac{\Delta \rho }{\rho}=(+1)\frac{\Delta m}{m}+ (-1)\frac{\Delta D}{D} + (-1)\frac{\Delta I}{I}\]\[\implies \frac{\Delta \rho}{\rho}= (+1 \times 1)+(-1 \times 1)+(-1 \times 0.5) \space percent\]
=> ( 1-1-0.5 ) %
=> (-0.5) %
Answer.

Answer 2

Am I right?

Answer 3

I mean wt is the answer?

Answer 4

That's the problem, i don't have an answer.. but know what ? i got 4.5% as answer!

Answer 5

how u gt?

Answer 6

Note: The above method can be applied only if the percentages are less than 5. That's cause it's an approximation.

Answer 7

thanx for telling
i didn't know that upto today.

Answer 8

so wt for more than 5?

Answer 9

Do it the long way. That is, write the expression for density got using values with error. write expn for actual density. relate all the respective quantities using the error %ges.

Answer 10

ok!