Question

A barometer reads 74 cm on a steel scale; the
room temperature is 25°C. The scale is
correcdly graduated for 0°С. Find the true
atmospheric pressure. (a steel = 1.2x 10-5/°C,
YHg = 1.8x 10-4/°C)
(a) 74.0042 cm (b) 76 cm
(c) 74.878 cm (d) 74.0222 cm

IIT. Questions..


​

Answer 1

$\fbox{\bf{Given:}}$

$Coefficient \:of\: linear \:expansion \:of\: steel (\alpha)=1.2 \times 10^{-4}\\ \\ \\Initial\: Temperature=0^{\circ}\\ \\ \\Room\: temperature=25^{\circ}$

$L_0 \:Initial\; length =74cm$

Solution

$\delta T=25^{\circ}-0^{\circ}\\ \\ \\=25^{\circ}$

$L=L_0(1+\alpha \delta T)\\ \\ \\=74(1+1.2 \times 10^{-5} \times 25)\\ \\ \\=74(1+0.003) \\ \\ \\=74(1.003)\\ \\ \\=74.222 cm \: of \: steel$

$\therefore P_{atm}=74.222cm\: of\:steel$

Answer 2

Hi mate sorry i don't know answer