The position coordinate of a particle which is confined to move along a straight line is given by s = 2t~ - 24t + 6, ,vhere s is measured in meters from
a convenient origin and t is in seconds. Determine (a) the time required for the
particle to reach a velocity of 72 m/s from its initiaJ condition at t = 0, (b) the ae-
celeration of the particle when v = 30 m/s, and (c) the net displacement of the
particle during the interval from t = l s to I - 4 s.

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.