find the solidification time of the two iron castings when both are poured

(with no superheats) into the sand molds at initial temperature 28°c.

(i) a slab shaped casting of 10 cm thickness, (ii) a sphere of 10 cm in dia. iron: freezing temp: 1540°c; l= 272 kj/kg; density = 7850 kg/m3 sand: c = 1.17 kj/kg-k; k = 0.865 w/mk; density = 1600 kg/m3

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?