Answer:
C
technically B too but youre teachers not that smart so there you go
 
        
             
        
        
        
Answer:
The intensity will be 1/9 as much.
Explanation:
The intensity of the light or any source is inversely related to the square of the distance.

Now according to the question the distance is increased by three times than,

Therefore,

Therefore the intensity will become 1/9 times to the initial intensity.
 
        
             
        
        
        
The letter D represents the wavelength
        
                    
             
        
        
        
Answer:
b) a = -k / m x
, c) d²x / dt² = - A w² cos (wt+Ф)
, d) and e)  T = 2π √m / k
h)   a = - A w² cos (wt+Ф)
Explanation:
a) see free body diagram in the attachment
b) We write Newton's second law
           Fe = m a
           -k x = ma
            a = -k / m x
c) the acceleration is
          a = d²x / dt²
      
       If x = A cos wt
         v = dx / dt = -A w sin (wt
+Ф)
         a = d²x / dt² = - A w² cos (wt+Ф)
d) we substitute in Newton's second law
         d²x / dt² = -k / m x
     
 We call
        w² = k / m
e) substitute to find w
      -A w² cos (wt+Ф) = -k / m A cos (wt+Ф)
       w² = k / m
 
Angular velocity and frequency are related
        w = 2π f
        f = 1 / T
        
  We substitute
       T = 2π / w
       T = 2π √m / k
g)    v= - A w sin (wt+Ф)
h) acceleration is
        a = - A w² cos (wt+Ф)