Answer:
The air exiting from the hairdryer is moving at a speed of 10 m/s.
Explanation:
The thrust generated by the hairdryer enables it to maintain an elevation angled at 5° from vertical; thus, we derive from the force diagram
by substituting 
, 
into the equation and resolving for 
we find:
This thrust is linked to the speed of air ejection 
through the equation
where 
signifies the rate of air ejection, which is known to be
and since 
,
by inserting these values into equation (2), we obtain the value of as:
resulting in
which indicates the air velocity discharged from the hairdryer.
The distinction lies in the fact that the candle emits an emission spectrum, while the book reflects an absorption spectrum. In the case of the book, light is observed from all directions, causing its reflection to be diffuse. Explanation: The light emitted by a candle originates from the heat of the flame, composed of a combination of emissions from a black body at that temperature along with emissions from the chemical elements within the candle. On the contrary, the light reflected off a book cover consists of the incident light spectrum minus the wavelengths that trigger electronic transitions in the cover's elements, resulting in dark areas on the spectrum. Consequently, the difference stems from the candle producing an emission spectrum, whereas the book showcases an absorption spectrum. For a book's cover to reflect light specularly, incident rays would need to reflect uniformly, creating dark areas. However, since light is observed from all directions when reflecting off a book, the result is diffuse reflection.
