A brass measuring tape is correct at 20 degree Celcius. The value obtained when the length of a field is measured with the rule at 50 degree Celsius appear to be 70.5m. What is the true length of the field. Take linear expansivity of brass 1.8×10^-5

Answer 1

I assume that is 1.8×10^-5 meters / deg centigrade ???
(Sure is hot out there)
deltaL/L = 1.8×10^-5 (50-20)
delta L = 1.8×10^-5 (30)(70.5) = 3807 *10^-5 = 0.03807 meters
so 70.5 - 0.038 meters or about 4 cm off