The figure shows four forces exerted on a moving box, moving at a constant speed. If the box continues to move with the same speed in the same direction, which statement is correct? F1 is equal to F4 and F2 is greater than F3.
F1 is equal to F2 and F3 is greater than F4.
F3 is equal to F4 and F1 is equal to F2.
F3 is equal to F4 and F1 is less than F2.

Ahair dryer is basically a duct in which a few layers of electric resistors are placed. a small fan pulls the air in and forces it through the resistors where it is heated. air enters a 1200 w hair dryer at 100 kpa and 22°c and leaves at 47°c. the cross-sectional area of the hair dryer at the exit is 60 cm2. neglecting the power consumed by the fan and the heat losses through the walls of the hair dryer, determine (a) the volume flow rate of air at the inlet and (b) the velocity of the air at the exit.