Question

a steel tape is calibrated at 20'c .on a cold day when the temperature is -15'c ,what will be percentage error in tape?

Answer 1

@tanvidais13 @csaltos @uncle

Answer 2

@HELLSGUARDIAN

Answer 3

whenever something is heated it expands & when cooled it contracts..so this case can be considered as the case of cooling..use equation \[change \in length=- \alpha \Delta T L\]
where L is original length ,\[\Delta T\] is change in temperature..and \[\alpha \] is coefficient of thermal expansion of steel..

when u have found the change in length the %ge error will be given as
(change in length/original length)*100
can u do the calculations?

Answer 4

hey i hav to find percentage error intape.

Answer 5

it will be
change in length/original length*100

Answer 6

bt length is nt mention only temp. is mention

Answer 7

L in this formula will be cancelled as it is in both numerator and denominator..

Answer 8

hey cn u solve it i'm nt getting u?

Answer 9

wait for 5 minute then i will upload the solution

Answer 10

okay

Answer 11

you get it?

Answer 12

no

Answer 13

okay tell me where u have the doubt?

Answer 14

change in length

Answer 15

orignal lenth is calibrated length
and change is occur when measured at -15c

Answer 16

have u got it

Answer 17

@UnkleRhaukus

Answer 18

hey ash can u hlp me out

Answer 19

Yes. Where do you have trouble understanding?

Answer 20

i'm nt geting the percentage error

Answer 21

All materials' length changes with temperature.
Change in length is given as
\[\Delta L=\alpha \Delta T L\]
Here \(\Delta T\) is the change in temp.
\(\alpha\) is the linear coefficient of thermal expansion.
Do you get this formula?

Answer 22

yes,after put result answer is nt coming

Answer 23

Let's find the change in length
\(\alpha \) for steel= \(10.8\times 10^{-6} / C\)
C= degree centigrade
What's \(\Delta T\) here?

Answer 24

35

Answer 25

it's -35. The length will decrease
\[\Delta T=(-15)-(20)=-35\]

Answer 26

\[\text{now find}\ \Delta L \ \text{in terms of L} \]

Answer 27

nt getting ANSWER CORRECT

Answer 28

Do you have the answer?

Answer 29

YES

Answer 30

Mind sharing here?

Answer 31

its -0.042%

Answer 32

Does you question mentions the value of alpha?

Answer 33

no
ur answer that u get

Answer 34

It's because of the value of alpha.
For steel it varies between \(11-13 *10^{(-6)} /C\)
Use \(12\times 10^{-6} /C\) and you'd get the answer

Answer 35

Do you get it?

Answer 36

99.94%

Answer 37

no .

Answer 38

i think that if we use difference in reading we get the answer.in place of length

Answer 39

@sauravshakya @shadowfiend @TuringTest

Answer 40

@experimentX