Achair weighing 150 rests on a level floor that is not
frictionless. a man pushes on the chair with a force = 43.0 that is
directed at an angle of 34.0 with the horizontal. assume that the
chair is stationary but is on the verge of sliding.
using newton's laws, calculate , the magnitude of the normal force
that the floor exerts on the chair.
what is the coefficient of static friction, , between the floor and
the chair? recall that the chair is on the verge of sliding.

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.