The steel pipe shown in Figure P8.67 has an outside diameter of 195 mm195 \mathrm{~mm}195 mm, a wall thickness of 10 mm10 \mathrm{~mm}10 mm, an elastic modulus of E=200GPaE=200 \mathrm{GPa}E=200GPa, and a coefficient of thermal expansion of α=11.7×10−6/∘C\alpha=11.7 \times 10^{-6} /{ }^{\circ} \mathrm{C}α=11.7×10−6/∘C. Using a=300 mm,b=900 mma=300 \mathrm{~mm}, b=900 \mathrm{~mm}a=300 mm,b=900 mm, and θ=70∘\theta=70^{\circ}θ=70∘, calculate the normal strains at HHH and KKK after a load of P=40kNP=40 \mathrm{kN}P=40kN has been applied and the temperature of the pipe has been increased by 25∘C25^{\circ} \mathrm{C}25∘C.
External defenses against microbial invasion include the ______ and the mucous membranes that line the ________, _______, and _______tracts.
An important effect that hunter-gatherer societies may have had on the environment was a. soil erosion. b. extinction. c. air pollution. d. All of the above
Choose the letter of the best answer. Birds are the only animals with a. scales. b. wings. c. feathers. d. a four-chambered heart.