Steel balls 12 mm in diameter are annealed by heating to 1150 K and then slowly cooling to 400 K in an air environment for which T? = 325 K and h = 20 W/m2/K. Assuming the properties of the steel to be k = 40 W/m2K, ? = 7800 kg/m3, and c = 600 J/kg/K, estimate the time required for the cooling process.

Amass of 1.5 kg of air at 120 kpa and 24°c is contained in a gas-tight, frictionless piston-cylinder device. the air is now compressed to a final pressure of 720 kpa. during the process, heat is transferred from the air such that the temperature inside the cylinder remains constant. calculate the boundary work input during this process.

The y form of iron is known as: a) ferrite b) cementite c) perlite d) austenite

Steel is coated with a thin layer of ceramic to protect against corrosion. what do you expect to happen to the coating when the temperature of the steel is increased significantly? explain.