An oil with k = 0.120 w/m ⋅ k, cp = 2,000 j/kg ⋅ k, rho = 895 kg/m^3, and µ = 0.0041 kg/m ⋅ s flows through a 2 cm diameter tube which is 2 m long. the oil is cooled from 60°c to 30°c. the mean flow velocity is 0.4 m/s, and the tube wall temperature is maintained at 24°c (µw = 0.021 kg/m ⋅ s). calculate the heat transfer rate.

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?