The collar a, having a mass of 0.75 kg is attached to a spring having a stiffness of k = 200 n/m . when rod bc rotates about the vertical axis, the collar slides outward along the smooth rod de. the spring is unstretched when s = 0. neglect the size of the collar. if the spring is unstretched when s = 0, determine the constant speed of the collar in order that s = 100 mm. also, what is the normal force of the rod on the collar? neglect the size of the collar.

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.