<span>C.
Sample C would be best, because the percentage of the energy 
in an
incident wave that remains in a reflected wave from this material 
is the
smallest.
The coefficient of absorption is the percentage of incident sound 
that's absorbed.  So the highest coefficient of absorption results in 
the smallest </span><span>percentage of the energy in an
incident wave that remains.
That's what you want. </span>
        
             
        
        
        
Answer:
I think it is <em><u>Rooting</u></em><em> </em><u><em>Reflex</em></u>
 
        
                    
             
        
        
        
The correct answer of this question is :  A) Change alternating current into direct current.
EXPLANATION :
As per the question, we are given vacuum tube. Vacuum tube can be of various types. Normally it contains two electrodes called cathode and anode which are enclosed in an evacuated glass chamber . There are also other types of vacuum tubes which contain extra electrodes like control grid .
The vacuum tube can be used as a rectifier. It means that it can be used as an electronic device which will convert alternating current into direct current. It may be a half wave rectifier or a full wave rectifier. Actually the direct current obtained during the rectification of alternating current is pulsating in nature.
Hence, the correct answer is that a vacuum tube can be used to change alternating current into direct current.
 
        
                    
             
        
        
        
If the two waves combine to produce ANY wave that smaller 
than either of the originals, that's destructive interference.
        
             
        
        
        
Answer:
75 rotations
Explanation:
f0 = 0, f = 3000 rpm = 50 rps, t = 3 s 
(a) use first equation of motion for rotational motion
w = w0 + α t
2 x 3.14 x 50 = 0 + α x 3 
α = 104.67 rad/s^2
(b) Let θ be the angular displacement
use second equation of motion for rotational motion
θ = w0 t + 1/2 α t^2
θ = 0 + 0.5 x 104.67 x 3 x 3
θ = 471.015 rad
The angle turn in one rotation is 2 π radian.
Number of rotation = 471.015 / (2 x 3.14) = 75 rotations