Chapter 9 - Solids and Fluids - Learning Path Questions and Exercises - Exercises - Page 349: 9

a). $(1)$ a cold day b). $1.9\times10^{5}N$

a). The correct choice is (1), a cold day, because tracks expand when temperature increases. b). L=8m, A=$2.5\times10^{-3}m^{2}$ $\Delta L=3.0\times 10^{-3}m$ Y=$210\times 10^{9}Pa$ So, $\frac{F}{A}=\frac{Y\Delta L}{L}$ or, $F=\frac{Y\Delta L A}{L}=1.9\times10^{5}N$ (after inserting the above values)