FIGURE 2 ...
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the
tw

Apparent and Absolute Brightness
The three stars Alnitak, Alnilam, and
Mintaka in the constellation Orion all
seem to have the same apparent bright-
ness from Earth. But Alnilam is actually
farther away than the other two stars.
CHALLENGE Which star has the
greatest absolute brightness? How do
you know?

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.