Water is boiled at atmospheric pressure by a horizontal polished copper heating element of diameter d = 5 mm and emissivity ε = 0.05 immersed in water. if the surface temperature of the heating wire is 350°c, determine the rate of heat transfer from the wire to the water per unit length of the wire.

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?