True, They contain old stars and posses little gas or dust
        
             
        
        
        
Answer:
   about 14.7°
Explanation:
The formula for the angle of the first minimum is ...
   sin(θ) = λ/a
where θ is the angle relative to the door centerline, λ is the wavelength of the sound, and "a" is the width of the door.
The wavelength of the sound is the speed of sound divided by the frequency:
   λ = (340 m/s)/(1300 Hz) ≈ 0.261538 m
Then the angle of interest is ...
   θ = arcsin(0.261538/1.03) ≈ 14.7°
At an angle of about 14.7°, someone outside the room will hear no sound.
 
        
             
        
        
        
Answer:
The angular speed of the reel is 11.33 rad/s
Explanation:
Given
The fisherman takes t = 8.4 s to wind distance x = 2.9 m into a circle radius of r = 3 cm = 0.03 m
Than the tangencial speed equals the change in the distance to the time
v = 
 = 
Knowing the tangencial velocity is proportional to the radius r and the angular velocity
v = r*w
w = 
 
 
 
        
             
        
        
        
The measurement of sound is in decibels.