Civil Engineering - UPSC Civil Service Exam Questions - Discussion

Discussion Forum : UPSC Civil Service Exam Questions - Section 7 (Q.No. 14)
14.
A 30 m steel tape was standardised at 20°C measurements of distances were taken as 15°C. If the coefficient of linear expansion of the material of the tape were 0.00, 00112 degree centigrade, then the error, due to temperature, per tape length would be
- 0.00, 00560 m
+ 0.00, 00560 m
+ 0.00, 16800 m
- 0.00, 16800 m
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
16 comments Page 1 of 2.

Rahul khan said:   8 years ago
Use formula, temp correction = L α t = 90x0.0000112x(15-20) = -0.00168 m.

Aman said:   7 years ago
Correction is negative than error is positive so I think C is correct option.

Ramvir said:   6 years ago
No @Aman.

Here, Tm>To so error will be -ve and correction will be +ve.

Kishan said:   6 years ago
Error of tape for temp. = Alpha x (tm-ts) x length of chain.

Arsha said:   6 years ago
@Rahulkhan:

Why L is taken as 90 when It's given as 30 in the question?

Koushal said:   5 years ago
In question asked per tap length so;
C/L = 00112*(15-20).
So. = -00560 will be answer.
So option A is correct.

Shivakant said:   5 years ago
C is correct.
m = 15'
To = 20'.

The temperature at the time of measurement is less than standard temperature so tape length will decrease and the error will be positive.

Correction is negative and error is possitive.
Per tape, length means per 30 m not per 1 meter what will be the error.
So it is 0.00168m.
(1)

Jaskaran said:   5 years ago
Let me explain>

The formula for correction C=α(tm -t)L.

So,α= 0.0000112.

Also l= 30m.

Also, temp measured = 15 degrees.
And temp star = 20 degree.

Solving we get -0.001680 but in the question it
Is for per metre tape length so divide by 30.

We get a correction - 0.0000560 but he has asked for error so + 0.0000560 is the correct answer.
(7)

Achint said:   5 years ago
It's not per meter tape length, it's per tape length So D is correct.

Narayan Ch. Saha said:   4 years ago
C is the correct answer.
(1)


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