Q1: A standard steel tape of length 30 m and cross-section 15 x 1.0 mm was standardised at 25°C and at 30 kg pull. While measuring a base line at the same temperature, the pull applied was 40 kg. If the modulus of elasticity of steel tape is 2.2 x 10⁶ kg/cm², the correction to be applied is

ANS:A - - 0.000909 m

Correction should be positive since we measured longer than actual it was, mean that suppose we have seen on tape length is 150m while measurement but actual it was more than that of 150m, let say 151 m actual therefore to obtain this from 150 to 151m.

We need correction positive.

So, the right option will be C. I think option A   is correct; as the tape elongated due to extra pull applied, hence the measured length will be less than the actual. The error is +ive but at the end of the question, "correction to be applied" has been asked. Which makes option A correct. The value of error is positive so we will deduct it from the final value, so the applied correction will be -0. 000909m. 30 m steel tape was standardized under 60 N pull at 65° F

It was suspended in 5 equal span during measurement. The mean temperature during measurement was 90° F and the pull exerted was 100 N. The area of the cross-section of the tape was 8 mm2. Find the true length of the tape, if, α = 6.3 * 10^6/F, E = 2 *105 N/mm2 and unit weight of steel = 78.6 kN/m3. is the correction option.
Correction due to pull = (Pm-P0)*L/AE.
= (40-30)*30*100/1.5*0.1*2.2*10^6.
= +0.0909. as pull you applied is more so the length measured will be less than true length and correction will be positive and error will be negative.